8LS User’s Guide Watlow Controls 1241 Bundy Blvd. Winona, MN 55987 Customer Service Phone: (800) 414-4299 Fax: (800) 445-8992 Technical Support Phone: (507) 494-5656 Fax: (507) 452-4507 Email: wintechsupport@watlow.com Part No. 10585-00. Revision 9.
Copyright © 1996 Watlow Anafaze Information in this manual is subject to change without notice. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form without written permission from Watlow Anafaze. Warranty Watlow Anafaze, Incorporated warrants that the products furnished under this Agreement will be free from defects in material and workmanship for a period of three years from the date of shipment.
Contents Overview 1 System Diagram.....................................................................2 Parts List ..........................................................................2 Safety .....................................................................................3 Introduction 5 Specifications.........................................................................7 Analog Inputs...................................................................7 Control Capability.................
PID Control Relay Outputs ..............................................28 Primary Screw Terminal Outputs ....................................28 Digital Outputs On The Screw Terminal Blocks.............29 Primary Analog Outputs ..................................................29 Analog Output Dip Switch Setting for 0-5v/4-20mA ..............................................................30 CPU Dip Switch...............................................................
Input Type........................................................................54 Pulse Sample Time ..........................................................55 Input Units .......................................................................55 Linear Scaling Menus ......................................................56 Input Offset ......................................................................58 Setup Control Menu...............................................................59 Heat/Cool PB .
Setting Up and Tuning PID Loops ........................................80 General PID Constants by Application..................................82 Troubleshooting 85 Stand Alone Systems .............................................................85 Checking Control Outputs ...............................................85 Checking Digital I/O........................................................85 Computer Supervised Systems ..............................................86 Computer Problems .........
Holding a Profile or Continuing from Hold.....................103 Resetting a Profile ............................................................104 Appendix B: 8LS-CP 105 Key Features ....................................................................105 System Configuration ............................................................106 Specifications.........................................................................108 Analog Inputs..............................................................
vi 8LS User’s Guide
Overview Overview This manual describes how to install, setup, and operate an 8LS controller. Included are six chapters, Appendixes describing the 8LS-CP (Carbon Potential) and the 8LS-RS (Ramp/Soak), and a glossary of terms. Each chapter covers a different aspect of your control system and may apply to different users. The following describes the chapters and their purpose. • Introduction: Gives a general description of the 8LS and its related specifications.
Overview System Diagram The illustration below shows how the parts of the 8LS are connected. When unpacking your system, use the diagram and parts list below to ensure all parts have been shipped. Please don’t hesitate to call Watlow Anafaze’s Technical Service Department if you have problems with your shipment, or if the 8LS components are missing or damaged.
Overview Safety Watlow Anafaze has made efforts to ensure the reliability and safety of the 8LS controller and to recommend safe usage practices in systems applications. Please note that, in any application, failures can occur. These failures may result in full control outputs or other outputs which may cause damage to or unsafe conditions in the equipment or process connected to the 8LS controller.
Overview 4 8LS User’s Guide
Introduction Introduction The 8LS is a powerful 1/4 DIN controller that delivers 8 fully independent loops of PID control. It can function as a stand alone controller and as the key element in a computer supervised data acquisition and control system. An LED front panel display and a touch keypad are available for local entry of control and other operating parameters. The 8LS can also be supervised by a computer or programmable controller through the standard serial interface.
Introduction Dual Output Standard: The 8LS includes dual control outputs for each loop with a second set of control constants for heating and cooling applications. Optional Ramp and Soak: The 8LS is available with a built in powerful Ramp and Soak programmer for batch processing. Optional Extruder or Carbon Potential: The 8LS is available with built in Extruder or Carbon Potential parameters for controlling these processes.
Introduction Specifications Analog Inputs Analog inputs 8, solid state, differential Optical isolation 120 Vac between inputs; 175 Vac from input to ground A/D converter Integrating voltage to frequency DC voltage range -10 to 60 mV. You can change it with scaling resistors to any range from 0 to 25V Resolution 0.02%, greater than 12 bits Accuracy 0.05% at 25°C Calibration Automatic zero and full scale Temperature coefficient Less than 50 ppm/C, 0.
Introduction Control Capability Number of loops 8, dual output Control outputs Cycle Time Proportioning, Distributed Zero Crossing, On/Off or Analog; all independently selectable for each loop Control action Reverse [heat] or Direct [cool], independently selectable for each loop Digital PID outputs Nominal 5 Vdc at 20 mA to drive optically-isolated solid-state relays Cycle time Programmable for each loop, 1-255 seconds Analog PID outputs Selectable 0 to 5 Vdc at 20 mA maximum or 4 to 20 mAdc 500
Installation Installation This section explains how to install the 8LS. The instructions are written for nontechnical users. If you are technically proficient and they seem simple, at least skim all of the instructions, so you don’t miss anything vital. These symbols are used throughout this manual: DANGER This symbol warns you of a hazard to human life. WARNING This symbol warns you of possible damage to property or equipment. NOTE This symbol denotes information you must know in order to proceed.
Installation Read This Before Installation DANGER Shut off power to your process before you install the 8LS. High voltage may be present even when power is turned off! Reduce the danger of electric shock after installation--mount the 8LS in an enclosure that prevents personal contact with electrical components. The 8LS measures input signals that are not normally referenced to ground, so the 8LS inputs and other signal lines can have high voltage present even when power is turned off.
Installation Mounting The 8LS The 8LS consists of a 1/4 DIN housing with a front plug in electronics module. The 8LS-OF (Open Frame) is suitable for sub-plate mounting inside an enclosure without a front panel. An 8LS-DK will supply the front panel keyboard with a 10-foot plug- in cable. For optimum performance when directly connecting thermocouple inputs, the unit should be protected from thermal shocks whenever possible.
Installation . Front Rear PIO LOOP 1 PROCESS 2 3 4 UNITS 5 6 7 TB4 8 3.78’’ 3.58 ’’ 90.9 mm 96 mm ALARM YES SETPOINT NO STATUS BACK OUTPUT% ENTER TB3 ALARM ACK MAN AUTO CHNG SP TB2 TB1 RAMP SOAK 3.58 ’’ 90.9 mm 3.78’’ 96 mm Side 3.78’’ 3.58’’ 96 mm 90.9 mm 9.4’’ 238.7mm 10.5’’ 266.
Installation 0.29’’ Remote Panel Mounting Dimensions Insert grommet 3.78’’ 7/16 dia 0.91’’ 125 dia 4 places 3.20’’ Notes: 1. Dashed line indicates panel outline. 2. Drill holes as indicated. 3. Install grommet and feed wire through grommet. 4. Attach panel using 4 #4 screws (from behind). Top 0.29’’ 3.78’’ 3.
Installation 2. Use 20 or 22 AWG size wire. The use of 16,18,20,22, or 24 AWG is permissible also. The power requirement is not a factor in the wire size. Only the mechanical strength and the ohmage of the wire may be factors to consider. Smaller or larger sizes are not easily installed, may be easily broken and/or cause intermittent connections. 3. Use shielded wire. The electrical shield is used primarily to protect from unwanted electrical noise.
Installation Wiring bundles of low power Watlow Anafaze circuits next to bundles of high power AC wiring should never be done. The physical separation of the high power circuits from the controllers should be of prime importance. In fact, most AC voltage high power circuits are installed in a separate panel. Cable Recommendations Use these cables or their equivalent.
Installation Noise Suppression When using the digital outputs from Watlow Anafaze multiloop controllers to energize dry contact electrical-mechanical relays with inductive loads, generation of RFI may become a problem. This may cause the 8LS display to blank out and then re-energize as if power had been momentarily turned off. It may also cause the CPU in the equipment to reset, losing the PID output levels.
Installation The above steps should eliminate any noise problems that might be present with using E-M relays. If, problems persists and/or any questions about the above steps arises, please call Watlow Anafaze Technical Service Department at (408) 724 3800. L1 L2 120 VAC 8LS + + K1 SSR 5 V Transorb NC K1 HORN NO .
Installation Terminal Block And Connector Layout The 8LS terminal blocks and connectors are assigned according to the following two pages. Subsequent sections provide detailed connection descriptions.
Installation RTB Connections The RTB provides the control outputs and additional digital inputs and outputs as follows: Terminal Function Terminal Function 1 +5 Vdc 2 +5 Vdc 3 Logic COM 4 Logic COM 5 Spare 6 Spare 7 Spare 8 Spare 9 PID 1 Out 10 Dig 30 Out 11 PID 2 Out 12 Dig 29 Out 13 PID 3 Out 14 Dig 28 Out 15 PID 4 Out 16 Dig 27 Out 17 PID 5 Out 18 Dig 26 Out 19 PID 6 Out 20 Dig 25 Out 21 PID 7 Out 22 Dig 24 Out 23 PID 8 Out 24 Dig 23 Out 25 Dig 5 Out
Installation NOTE When using the RTB, proper polarity of the flat ribbon cable is necessary for correct pin terminations. Install the red marker indicating pin #1 to the left when terminal #1 of the RTB is to the left. The flat ribbon cable should have the red marker down when installing it on the back of the 8LS. To confirm proper polarity, check that pin #1 is +5vdc with respect to pin #3. Analog Inputs Connecting analog signals to the 8LS is normally straightforward.
Installation Source Impedance Each sensor has a certain output impedance which is effectively connected across the 8LS input amplifier when a measurement is made. To reach the rated accuracy, the maximum source impedance should not exceed 500 ohms. Consult Watlow Anafaze for operation with higher source impedance. Input Scaling The 8LS contains an area that can be used to install resistors to scale input voltages and convert milliamp inputs to match the -10 to 60mv (16.7% to 100%) input range.
Installation Resistor Installation For scaling resistors the body of the resistor goes vertically into the hole with the white silk screen. The lead on the top then goes into the adjacent indicated hole. The resistor positions are highlighted.
Installation Voltage Inputs DC Voltage inputs should be connected with the positive side to the High terminal and the negative side to the Low terminal. The input range is -10 to +60 mV. Signals greater than 60 mv must be scaled with resistors to match the input full scale to 60 mv. The scaling resistor RA is selected as the voltage dropping and/or current limiting resistor. RB is selected for the 60 mv full scale dropping resistor. It should normally be less then 300Ω and no greater then 1000Ω.
Installation RTD Inputs The standard industrial RTD is a 100 ohm Platinum three wire assembly. We highly recommend using the 3-wire RTD. The 8LS will be configured for the standard three wire RTD input. Watlow Anafaze offers two standard DIN 385 Curve RTD input ranges, as shown in the table below: RTD Type Input Range Display Resolution RTD1 -100.0 to +300.0 °C 0.1° -148.0 to +572.0 °F -120.0 to 840.0 °C RTD2 0.2° -184.0 to +1544.0 °F RTD Range resistors are Watlow Anafaze factory stock in .
Installation The range of the standard IRSM is 0-1000 degrees F with an output of 0-10ma dc. The input of the Watlow Anafaze 8LS is configured for a 010madc input. To use more than four IRSM's with the 8LS, use an external power supply of 8-15vdc. If desired, a second input may be used to monitor the internal IRSM ambient temperature. Consult Watlow Anafaze for more information.
Installation The Belden cable part number 88760 is highly recommended for the connection of the carbon probe to the 8LS. An equivalent cable may be used. Chas TB4 Gnd 6 5 4 3 2 1 1 2 T/C + - 4 Probe + _ 6 3 5 Shield Probe Cable Belden #88760. Connect Shield to TB4-6 Chassis Ground. No. of CP Loops 26 8LS User’s Guide T/C input Loop Number Carbon Probe Input Loop No.
Installation Control Outputs WARNING Control outputs are connected to the 8LS logic ground. Be careful when you connect external devices that may have a low side at voltage other than controller ground, since you may create ground loops. If you expect grounding problems, use isolated solid state relays and isolate the control device inputs. PID Output Termination TB (Primary) or Flat Ribbon (Secondary) The 8LS PID control outputs are Dual Outputs for each loop.
Installation Pid Control Relay Outputs Typical ON/OFF, TP, DZC control outputs utilize external opticallyisolated solid-state relays. These relays use a 3 to 32vdc input for control and can be sized to switch up to 100amps at 480vac. For larger currents these relays can be used to drive contactors. Primary Screw Terminal Outputs The primary PID positive output for each loop is located on the screw terminal blocks and labeled Ctl Out 1+ through Ctl Out 8+. The negative side of the output is Logic Ground.
Installation Digital Outputs On The Screw Terminal Blocks NOTE Alarms and events outputs are sinking +5vdc to ground when the output is ON. They should be connected to the minus (-) side of SSRs. Connections are made as follows: Screw Terminal Block 2 Pin # Digital Out 1 (Alarm ON/OFF) 16 Digital Out 2 (Event On/Off) 18 +5Vdc Supply 21 PID Ctl Out 1+ (TP or On/Off) 4 Logic Ground 1 Alarm SSR 1 Event SSR 2 _ + _ + Control SSR 3 _ + See Terminal Block and Connector Layout.
Installation second is down, the output is in current mode. Thus if switch 3 is down and 4 is up on the dip switch package near the rear panel, then channel 3 is set for voltage. Rear DIP Switch F 1O 8 Odd Front DIP Switch F 1 8 Even O CPU DIP Switch 8 o 1F Output switches are set to voltage mode; in CPU switch all special features are set to Off.
Installation CPU Dip Switch WARNING Normal mode of operation is for all positions to be Off. Positions that are On will effect the 8LS normal operation mode. Position 1 ON--Clears the battery backed RAM and re-initializes the factory default values into the RAM. 1. Turn off power. 2. Set DIP switch position 1 ON. 3. Turn on power for 10 seconds, and then turn it off. 4. Set DIP switch position 1 OFF. 5. Turn on power. Positions 2 to 8 are not used for normal 8LS operations. All positions must be OFF.
Installation Connections are made as follows: Remote Terminal Block Or Ribbon Cable Pin PID Ctl Out 1 9 PID Ctl Out 2 11 +5Vdc Supply 1 32 8LS User’s Guide SSR 1 - + SSR 2 - +
Installation Communications Set-up and Connections The 8LS offers two types of serial communications: RS- 232 and RS485. Up to 32 addresses can be set in the 8LS for one communication line. RS-232 can not be used for more than 1 controller. Unless otherwise specified in the purchase order, units are shipped configured for RS-232. They may be easily modified to RS- 485 by moving a cable and a jumper plug.
Installation RS-485 Description And Connections The RS-485 is a voltage balanced long distance multi-point transmission interface. It may use 2 or 4 lines depending on system requirements. The 8LS uses four lines [two lines can be accommodated on special order -- contact Watlow Anafaze]. RS-485 Description The EIA Standard RS-485 specifies only the electrical characteristics of generators (transmitters) and receivers for use in digital multi-point systems.
Installation RS-485 Connections Connection of Watlow Anafaze controllers to a system computer requires an interface at the computer to convert RS-232 levels to RS485. Watlow Anafaze recommends two options: • B&B Electronics 485OIC with 485PS2 or 485OISPR with 485PS. • Black Box Model LD485A. The LD485A should be configured for DCE operation, with the RTS/CTS delay jumper in the "on" position. Watlow Anafaze can supply this converter configured and checked out with the system on request.
Installation A termination resistor is required at each end of the transmission line. This is accomplished by applying a 200Ω resistor across the line at the farthest point from the computer transmitter. Check with Watlow Anafaze for setting the Black Box SW2 to the "term" position to terminate the computer receive line. The fifth wire for RS-485 communications is recommended for noisy environment. NOTE Connect the cable shields to equipment ground only at the 8LS controller sites.
Using the 8LS Using the 8LS This Chapter will show you how to use the 8LS from the front panel. Front Panel The 8LS front panel provides a convenient interface with the controller for both viewing the process conditions and operating the controller. You can program and operate the 8LS with the front panel keys shown below, or you can use ANASOFT, a program designed specifically for Watlow Anafaze controllers. LOOP 1 Yes Select a menu Answer Yes to Yes/No prompts.
Using the 8LS Front Panel Keys YES Yes/Up Press Yes to • Select a menu when prompt is blinking • Answer Yes to Yes/No prompts • Increase a number or choice you are editing NO No/Down Press No to • Skip a menu when prompt is blinking • Answer No to Yes/No prompts • Decrease a number or choice you are editing BACK Back Press Back to • Abort editing • Return to a previous menu ENTER Enter Press Enter to • Store data or menu choice after editing • Proceed to the next menu ALARM ACK Alarm Ack Press
Using the 8LS CHNG SP Chng SP Press Chng SP to • Adjust the setpoint on displayed loop MAN AUTO Man/Auto Press Man/Auto to • Toggle loop status between Manual and Auto • Adjust output power level of loops in Manual mode RAMP SOAK Ramp/Soak Press Ramp/Soak to • Assign a Ramp/Soak profile to selected loop • Perform operations on profile you have assigned NOTE If the Ramp/Soak function is not installed, this key has no function.
Using the 8LS Displays The next section discusses the 8LS displays: • Bar Graph display • Single Loop display • Scanning display • Alarm display Bar Graph Display This is the default display on power-up. It provides a system overview by displaying a deviation bar graph for each loop. Loop status including acknowledged alarms, manual or auto are also displayed. LOOP 1 PROCESS 2 3 4 5 UNITS 6 7 8 AM A M A A AM ALARM SETPOINT STATUS OUTPUT% The upper display shows the Bar Graph for each loop.
Using the 8LS The table below shows the status symbols for the Ramp and Soak option. Loop Status Symbol Description Loop Function Loop Display START S Ramp/Soak profile loaded, ready to start RUN R Ramp/Soak profile is running HOLD H Ramp/Soak profile is in hold WAIT W Ramp/Soak loop is waiting for a trigger state to be satisfied TOLERANCE ERROR T Ramp/Soak loop is out of tolerance and loop is in hold If an acknowledged alarm exists, the Bar Graph is replaced by an alarm symbol.
Using the 8LS The table below shows the alarm symbols. Alarm Symbol High process High deviation Low deviation Low process Tolerance error T The Alarm display interrupts any system display. If more than one alarm is present, the first one is shown. When you press the Alarm Ack key, the flashing stops but the alarm indicator remains as long as the alarm condition exists.
Using the 8LS Operator Menus You can perform these tasks from Single Loop display. Changing the Setpoint Press CHNG SP from the loop you want to change. This display appears: LOOP PROCESS UNITS 5 1 2 3 4 5 6 SP ? ALARM 7 8 25 SETPOINT STATUS OUTPUT% • Press Yes to change the setpoint. • Press Yes or No to change the setpoint value. • Press Enter to save your changes and return to Single Loop display. • Press No or Back to return to Single Loop display without saving the new setpoint.
Using the 8LS If you have set the current loop to Manual control, this display appears after you press Enter: LOOP PROCESS UNITS 6 SET MAN 1 2 3 OUT ALARM 4 5 H T ? 6 7 8 0 SETPOINT STATUS OUTPUT% • Press Yes to change the output power. • Press Yes or No to select a new power output level.
Setup Setup The Setup menus let you change the 8LS detailed configuration information. If you have not set up a modular system before, or if you don’t know what values to enter, please read the next section first, Tuning and Control, which contains PID tuning constants and useful starting values. How to enter the Setup menus? 1. In Single Loop display, select the loop you wish to edit. 2. Enter this pass sequence: Enter, Alarm Ack, and Chng SP. ENTER ALARM ACK CHNG SP 3. The first Setup menu appears.
Setup Setup Globals? Setup Input? Save as job# ? Input type? Restore Job# ? Input smplt? Alarm delay? (only Pulse) Input unit? Hi PV? R/S time base? (only Linear & Pulse) Panel lock? (only Linear & Pulse) Power up outs? (only Linear & Pulse) Hi RDG? Lo PV? Lo RDG? Contrllr addr? Comm err chk? (only Linear & Pulse) Setup Outputs? Setup control? Control PB HT ? Comm baud? Typ HT C L Alarms HP? ? Control TI HT ? Outputs Control TD HT ? Outputs Act HT CL ? Control FIL HT ? Outp
Setup Setup Global Parameters Menu The Setup global parameters menu looks like this: LOOP PROCESS UNITS SETUP 1 2 3 4 5 6 7 8 GLOBALS? ALARM SETPOINT STATUS OUTPUT% Answering Yes to this prompt gets you into the globals submenus. Below is the setup global parameters menu tree. Notice the default values inside the boxes.
Setup Save as Job Use this menu to save the job information for every loop to one of eight jobs in the battery-backed memory. LOOP PROCESS UNITS SAVE AS 1 2 3 4 5 6 JOB #? ALARM 7 8 1 SETPOINT STATUS OUTPUT% Selectable Range: 1-8. Restore a Job Use this menu to load a job from the memory . LOOP PROCESS UNITS RESTORE 1 2 3 4 5 6 7 8 JOB # ? 1 ALARM SETPOINT STATUS OUTPUT% Selectable Range: The last job number or job 1.
Setup Set R/S Time Base Use This menu to set the global ramp and soak time base to units of hours and minutes or minutes and seconds. All time entries in r/s profiles will assume the units you set here. LOOP PROCESS UNITS R/S TIME 1 2 3 4 5 6 7 8 BASE?H/M ALARM SETPOINT STATUS OUTPUT% Selectable values: Hours and minutes or minutes and seconds. NOTE This prompt appears only if your 8LS has the Ramp and Soak option installed.
Setup WARNING Set safe start up conditions. Do not use memory startup if there is any chance the process could start in an unsafe state. Controller Address Use this menu to set the 8LS controller address. This address is used for communications and each 8LS in a system must have a different address. Begin with address 1 for the first controller and assign each subsequent controller the next higher address.
Setup Communication Baud Rate Use this menu to set the communications baud rate. LOOP PROCESS UNITS COMM 1 2 3 4 5 6 BAUD? ALARM 7 8 96 SETPOINT STATUS OUTPUT% Selectable values: 2400 or 9600. NOTE If you are using ANASOFT, be sure to set ANAINSTL to the same baud rate you set in this menu. Communication Protocol Use this menu to set the protocol type to either Allen Bradley or ANAFAZE.
Setup EPROM Version Use this menu to see the controller’s EPROM version and checksum. LOOP PROCESS UNITS 8LS-RS 1 2 3 4 5 6 7 8 V3.
Setup Setup Inputs Menu The Setup input main menu lets you access menus which change loop input parameters: • Input type • Engineering units • Scaling The Setup inputs menu looks like this: LOOP PROCESS UNITS 1 SETUP 1 2 3 4 5 6 7 8 INPUT? ALARM SETPOINT STATUS OUTPUT% Answering Yes to this prompt, gets you into the Inputs submenus. Below is the setup inputs menu tree. Notice the default values inside the boxes.
Setup Input Type Use this menu to configure the input sensor for each loop as one of these input types: • Thermocouple types (J, K, T, S, R, B, and N) • RTD. Two ranges: RTD1 (Platinum class A: DIN 43760-1980, Alpha=.00385), and RTD2 (Platinum class B: DIN 43760-1980, Alpha=.00385). • Linear and Pulse inputs. • Skip. Scanning display doesn’t show loops you set to Skip.
Setup Pulse Sample Time You can connect a digital pulse signal of 20 KHz to the controller’s pulse input. Use this menu to specify the pulse sample period. Every sample period, the number of pulses the controller receives is divided by the sample time. The controller scales this number and uses it as the pulse loop’s PV. LOOP PROCESS 1 INPUT 1 2 3 4 5 UNITS 6 7 8 SMPLT? 1 ALARM SETPOINT STATUS OUTPUT% Selectable range: 1-20 seconds.
Setup Linear Scaling Menus NOTE The next four menus appear only for Linear or Pulse loops. For all inputs automatic scaling is provided. To set the scaling enter a high process variable in engineering units and a corresponding high reading. Then enter a low process variable in engineering units and a corresponding reading. Using points as near as possible to zero and full scale is best. After these entries the process variable, the setpoint and alarms will all be in engineering units.
Setup Low RDG Display LOOP PROCESS UNITS 1 LO RDG 1 2 3 ? ALARM 4 5 6 7 8 0 SETPOINT STATUS OUTPUT% Selectable range: 0-9999. The low input reading is referenced to 60mV and is calculated using this equation: (Sensor output @ Low PV) LOW RDG = (1000) * 60 mV Linear Input Scaling Example: Problem: You want to connect a pressure sensor to be able to read pressure directly in PSI. The sensor has an output of 4-20mA over a range of 100-400PSI. The 4-20mA is converted to 12-60mV.
Setup Input Offset NOTE The next menu appears only for Thermocouple or RTD loops. Use this menu to make up for the input signal’s inaccuracy. For example, at temperatures below 400ºF , a type J thermocouple may be inaccurate ("offset") by several degrees. To correct for offset errors, change the factory default setting to a positive or negative value for the loop you are editing. A positive value increases the reading and a negative value decreases it.
Setup Setup Control Menu The Setup Control menu allows you to set control parameters for both heat and cool outputs of the selected loop. These are the parameters you can edit. • Proportional Band • Integral • Rate • Output Filter • Spread between heat and cool outputs The Setup Control menu looks like this: LOOP PROCESS 1 1 UNITS SETUP 2 3 4 5 6 7 8 CONTROL ? ALARM SETPOINT STATUS OUTPUT% Answering Yes to this prompt gets you into the control submenus. Below is the setup control menu tree.
Setup Heat/Cool PB Use this menu to set the Proportional Band. LOOP PROCESS UNITS 1 CONTROL 1 2 3 PB ALARM 4 H T 5 6 ? 7 8 50 SETPOINT STATUS OUTPUT% Heat/Cool TI Use this menu to set the Integral Term. LOOP PROCESS UNITS 1 CONTROL 1 2 3 4 H T TI ALARM 5 6 7 8 ? 180 SETPOINT STATUS OUTPUT% Selectable range: 0-5000 seconds. Heat/Cool TD Use this menu to set the Derivative constant.
Setup Heat/Cool Spread Use this menu to set the spread between the heat and cool output and the spread of the On/Off control action. LOOP PROCESS UNITS 1 CONTROL 1 2 3 4 SPR? ALARM 5 6 7 8 10 SETPOINT STATUS OUTPUT% Selectable range: 0-255 engineering units.
Setup Setup Outputs Menu The Setup Outputs Menu allows you to edit output parameters such as: • Output type • Cycle time • Control action • Output level limit • Output limit duration • Heat/Cool nonlinear output curve • Terminal Block or Ribbon The Setup Outputs Menu looks like this: LOOP PROCESS UNITS 1 SETUP 1 2 3 4 5 6 7 8 OUTPUTS? ALARM SETPOINT STATUS OUTPUT% Answering Yes to this prompt gets you into the Setup Outputs submenus. Below is the setup outputs menu tree.
Setup Output Type Use this menu to to set the output type. LOOP PROCESS UNITS 1 OUTPUTS 1 2 3 TYP ALARM 4 5 H T ? 6 7 8 TP SETPOINT STATUS OUTPUT% Selectable values: The next table shows the available output types. Display Code Output Type Definition TP Time Proportioning Percent output is converted to a percent duty cycle over the programmed cycle time. DZC Distributed Zero Crossing. Available only on secondary (50 pin Ribbon output).
Setup Output Action Use this menu to select the control action for the current output loop. The default is Reverse for heat outputs and Direct for cool outputs. LOOP PROCESS UNITS 1 OUTPUTS 1 2 3 ACT ALARM 4 5 H T 6 7 ?REV 8 SETPOINT STATUS OUTPUT% Selectable values: Reverse or Direct. Output Limit The output from each loop's dual heat/cool output may be limited to a value less than 100%. This level may not be exceeded by the PID control action.
Setup Output Limit Time Use this menu to set the time limit for the output limit. LOOP PROCESS UNITS 1 OUTPUTS 1 2 3 LTM ALARM 4 5 6 7 8 ? C H T SETPOINT STATUS OUTPUT% Selectable values: 1-999 seconds or C (Continuous). Nonlinear Output Curve Use this menu to select one of two nonlinear output curves for nonlinear processes.
Setup Heat Output Use this menu to select the Terminal Block or the Flat Ribbon for the heat output termination. The heat output is usually defaulted to the screw terminals of TB2, while the cool output is on the 50 pin flat ribbon connections of P10. However, you can switch the outputs, so heat is switched to the flat ribbon output, and cool--to the screw terminals of TB2.
Setup Setup Alarms The Setup Alarms main menu lets you access menus which change the alarm functions for the selected loop. You can edit these parameters: • High process alarm • Deviation band alarm • Low process alarm • Alarm Deadband The Setup Alarms main menu looks like this: LOOP PROCESS UNITS 1 SETUP 1 2 3 4 5 6 7 8 ALARMS? ALARM SETPOINT STATUS OUTPUT% Answering Yes to this prompt, gets you into the Alarms submenus. Below is the setup alarms menu tree.
Setup Alarm Types Global Alarms Global alarms occur when a loop alarm, set to Alarm, is unacknowledged, or when there are any unacknowledged failed sensor alarms. (If an alarm occurs, the 8LS front panel displays an appropriate alarm code). Even if the alarm condition goes away, the global alarm stays on until you use the Alarm Ack key (or ANASOFT) to acknowledge it. Process Alarms Process alarms include high and low deviation and high and low process alarms.
Setup High Process Alarm Setpoint Use this menu to select the setpoint at which the high process alarm activates. The high process alarm activates when the process variable (PV) goes above the high process setpoint. It deactivates when the PV goes below the high process setpoint minus the deadband value, if you have set one. LOOP PROCESS UNITS 1 ALARMS 1 2 3 4 5 6 7 8 HP? 1000 ALARM SETPOINT STATUS OUTPUT% Selectable values: Any point within the scaled sensor range.
Setup Deviation Band Alarm Use this menu to set the deviation bandwidth, a positive and negative alarm point relative to the setpoint. If the setpoint changes, the alarm points also changes. You can assign a separate digital output to the high and low deviation alarm setpoints. (For example, the high deviation alarm turns on a fan, and a low deviation alarm turns on a heater. LOOP PROCESS UNITS 1 ALARMS 1 2 3 4 5 DEV ? ALARM 6 7 8 10 SETPOINT STATUS OUTPUT% Selectable values: 0-255.
Setup Low Deviation Alarm Output Number Use this menu to assign a digital output which activates when the loop is in low diviation alarm. LOOP PROCESS 1 LO 1 2 3 4 UNITS DEV 5 6 7 8 OUTPN ? 0 ALARM SETPOINT STATUS OUTPUT% Selectable values: 0-30. Low Process Alarm Setpoint Use this menu to set a low process alarm setpoint. The low process alarm activates when the process variable (PV) goes below the low process alarm setpoint.
Setup Low Process Alarm Output Number Use this menu to assign the digital output that activates when the loop is in low process alarm. LOOP PROCESS 1 LO 1 2 3 UNITS PRO 4 5 6 7 8 OUTPN? 0 ALARM SETPOINT STATUS OUTPUT% Selectable values: 0-30. Alarm Deadband Use this menu to set an alarm deadband. This deadband value applies to the high process, low process, high deviation, and low deviation alarms for the loop you are editing.
Setup Test I/O The Test I/O main menu lets you view menus which can help you test the digital inputs and the digital outputs. The main menu looks like this: LOOP PROCESS UNITS TEST 1 2 3 4 5 6 7 8 I/O ? ALARM SETPOINT STATUS OUTPUT% Answering Yes to this prompt gets you into the I/O test submenus. Below is the menu tree. Notice the default values in the boxes.
Setup Test Output Use this menu to select one of the 30 digital outputs for manual operation. LOOP PROCESS UNITS TEST OUT 1 2 3 4 5 NR = ALARM 6 7 8 1 SETPOINT STATUS OUTPUT% Selectable values: 1-30. Digital Output Test Use this menu to toggle the state of a digital output between On and Off. LOOP PROCESS DIG 1 2 3 UNITS OUT 4 5 6 7 8 NR01? OFF ALARM SETPOINT STATUS OUTPUT% Selectable values: On, Off. NOTE Before leaving this menu, turn Off all the outputs you have turned On.
Tuning and Control Tuning and Control Introduction This chapter explains PID control and supplies some starting PID values and tuning instructions, so that you can use control parameters appropriate for your system. If you would like more information on PID control, consult the Watlow Anafaze Practical Guide to PID. The control mode dictates how the controller responds to an input signal. The control mode is different from the type of control output signal (like analog or pulsed DC voltage).
Tuning and Control Control Modes The next sections explain the different modes you can use to control a loop. On/Off Control On/Off control is the simplest way to control a process; a controller using On/Off control turns an output on or off when the process variable reaches a certain limit above or below the desired setpoint. You can adjust this limit, since Watlow Anafaze controllers use an adjustable spread.
Tuning and Control However, a process which uses only Proportional control may settle at a point above or below the setpoint; it may never reach the setpoint at all. This behavior is known as “offset” or “droop”. (This diagram shows a process under proportional control only.) Proportional and Integral Control For Proportional and Integral control, use the Integral term, or Reset, with Proportional control.
Tuning and Control Proportional, Integral and Derivative Control For an improved level of control, use Derivative control with Proportional or Proportional and Integral control. Derivative control corrects for overshoot by anticipating the behavior of the process variable and adjusting the output appropriately. For example, if the process variable is rapidly approaching the setpoint, Derivative control reduces the output, anticipating that the process variable will reach setpoint.
Tuning and Control Distributed Zero Crossing (DZC) DZC output is essentially a Time Proportioning output. However, for each AC line cycle the controller decides whether the power should be On or Off. There is no Cycle Time since the decision is made for each line cycle. Since the time period for 60 Hz power is 16.6 ms, the switching interval is very short and the power is applied uniformly. Switching is done only at the zero crossing of the AC line, which helps reduce electrical “noise”.
Tuning and Control Setting Up and Tuning PID Loops After you have installed your control system, tune each control loop and then set the loop to automatic control. (When you tune a loop, you choose PID parameters that will best control the process.) If you don't mind minor process fluctuations, you can tune the loop in automatic control mode. This section gives PID values for a variety of heating and cooling applications. Tuning is a slow process.
Tuning and Control Integral Term (TI) Settings This table shows TI settings vs. Reset settings. TI (secs./repeat) Reset (repeats/min) TI (secs./repeat) Reset (repeats/min) 30 2.0 210 0.28 45 1.3 240 .25 60 1.0 270 .22 90 .66 300 .20 120 .50 400 .15 150 .40 500 .12 180 .33 600 .10 As a general rule, use 60, 120, 180, or 240 as a starting value for the TI. Derivative Term (TD) Settings This table shows Derivative term (TD) versus Rate Minutes (RM); Rate=TD/60. TD (secs.
Tuning and Control General PID Constants by Application This section gives PID values for many applications. They are useful as control values or as starting points for PID tuning. Proportional Band Only (P) PB: Set the PB to 7% of the setpoint (SP) (Example: Setpoint = 450, so Proportional Band = 31). Proportional with Integral (PI) PB: Set the PB to 10% of SP (Example: Setpoint = 450, so PB = 45). Set TI to 60. Set TD to Off. Set the Output Filter to 2.
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Tuning and Control 84 8LS User’s Guide
Troubleshooting Troubleshooting NOTE If you need to return the 8LS to Watlow-Anafaze, please call first for a Returned Materials Authorization (RMA) number. This number helps us track your equipment and return it to you as soon as possible. Stand Alone Systems If the unit has no display, check the 120vac power supply. If you insert a spare unit, enter the values from the original unit. You can store and enter these values using a standard IBM PC or compatible computer and ANASOFT software.
Troubleshooting Computer Supervised Systems These four items must work together to operate the 8LS: 1. The 8LS 2. The computer including the RS-232 or other serial interface 3. The communications link 4. The computer software If the system does not work on initial startup, check the 8LS, the computer, and the serial link. First, check the 8LS in the stand alone mode. If there’s a problem, return the 8LS to Watlow-Anafaze for service. The serial link must be RS485 when using more than one 8LS.
Troubleshooting If you write your own software, first write a routine that sends and receives display commands to and from the 8LS. The protocol includes all characters, so the display should show the hexadecimal values of the data sent in both directions. If you have problems with the software you write, you can use this program to test your communications. ANASOFT If ANASOFT is not working, check these things first: 1.
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Appendix A: Ramp Soak Appendix A: Ramp Soak Introduction This Appendix will teach you how to set up and use Ramp/Soak profiles in 8LS controllers. The Ramp/Soak feature turns your 8LS into a powerful and flexible batch controller. The Ramp/Soak feature lets you program the controller to change a process setpoint in a preset pattern over time. This preset pattern, or temperature profile, consists of several segments.
Appendix A: Ramp Soak Specifications Number of possible profiles 8 Number of times to repeat a profile 1-99 or continuous Number of segments per profile 1-20 Number of triggers per segment Up to 2 Type of triggers Latched/ Unlatched Number of possible inputs for triggers 8 Number of events per segment 4 Number of possible outputs for events (At least one of these outputs must be used for control) 30 Configuring Ramp/Soak This section will teach you how to set up R/S profiles.
Appendix A: Ramp Soak Setting the R/S Time Base The R/S time base menu is in the Setup Globals main menu. Use this menu to set the time base in all your R/S profiles. LOOP PROCESS R/S 1 2 3 UNITS TIME 4 5 6 7 8 BASE? H/M ALARM SETPOINT STATUS OUTPUT% Selectable Values: H/M (Hours/Mins) or M/S (Mins/Secs). Editing R/S Parameters You can reach the rest of the menus in this section from the Setup Ramp/Soak profile main menu.
Appendix A: Ramp Soak Copying the Setup from Another Profile Use this menu to setup similar profiles quickly, by copying a profile to another one. LOOP PROCESS UNITS R/S PRO 1 2 3 4 5 6 7 8 COPY? H ALARM SETPOINT STATUS OUTPUT% Selectable Values: A to H. Editing the Tolerance Alarm Time Use this menu to set a tolerance time that applies to the entire profile.
Appendix A: Ramp Soak Editing the Ready Setpoint When you assign a profile to a loop, the profile doesn’t start immediately; instead, it goes to the ready segment (segment 0) and stays there until you put the profile in Start mode. You can set a setpoint, assign events, and set event states for the ready segment. Use this menu to set the ready segment setpoint. LOOP PROCESS UNITS A READY 1 2 3 4 5 6 7 8 SP? OFF ALARM SETPOINT STATUS OUTPUT% Selectable Values: -999 to 9999, or Off.
Appendix A: Ramp Soak Choosing an External Reset Input Use this menu to select an external reset input. Toggle the input to reset a profile to Ready state when it is in Run, Hold, or Wait mode. You can make any of the eight digital inputs the external reset input. LOOP PROCESS UNITS A EXTRST 1 2 3 4 5 6 7 8 IN NR? 0 ALARM SETPOINT STATUS OUTPUT% Selectable Values: 0-12. Editing a Segment Each profile is made up of several segments (up to 20). Use this menu to choose the segment to edit.
Appendix A: Ramp Soak Setting a Segment Setpoint Use this menu to set a setpoint for the segment you are editing. The process will go to this setpoint by the end of the segment time. LOOP PROCESS UNITS A SEG 01 1 2 3 4 5 6 7 8 SP? OFF ALARM SETPOINT STATUS OUTPUT% Selectable Values: -999 to 9999, or Off (no segment setpoint). Configuring Segment Events You can assign up to four digital outputs—Events—to each segment.
Appendix A: Ramp Soak Editing Event Outputs This menu appears only if you answered YES to the previous menu. Use it to assign a digital output to each event. Assign digital outputs that are not being used for PID control. LOOP PROCESS UNITS A S01EV1 1 2 3 4 5 6 7 8 DOUT?NO ALARM SETPOINT STATUS OUTPUT% Selectable Values: 1-30, except those IN USE, or No (no event). Changing Event States Use this menu to assign an output state to each event: On (High) or Off (Low).
Appendix A: Ramp Soak Assigning an Input to a Trigger This menu appears only if you answered YES to the Edit Segment Triggers menu. Use it to assign one of the controller’s eight digital inputs to a segment trigger. You can assign any digital input to ant trigger. You can also assign the same digital input to multiple triggers. LOOP PROCESS UNITS A S01TR1 1 2 3 4 5 6 7 8 DIN? NO ALARM SETPOINT STATUS OUTPUT% Selectable Values: 1-12, or No (no input assigned).
Appendix A: Ramp Soak Setting Segment Tolerance Use this menu to set a positive or negative tolerance value for each segment. this value is displayed in the engineering units of the process and is a deviation from the setpoint. Positive Tolerance Value Negative Tolerance Value PV out of tolerance PV within tolerance Setpoint Setpoint PV within tolerance PV out of tolerance • If you enter a positive tolerance, the process is out of tolerance when the PV goes above the setpoint plus the tolerance.
Appendix A: Ramp Soak Using Ramp/Soak This section explains how to assign a profile to a loop, how to put a profile in Run, Continue, or Hold mode, how to reset a profile, and how to display profile statistics. The next figure shows the Ramp/Soak key menus.
Appendix A: Ramp Soak Assigning a profile the first time To assign a profile to a loop that doesn’t have a profile, follow these steps: 1. In Single Loop display, switch to the loop you want to edit. 2. Press the RAMP/SOAK key. The assigning menu appears. (See menu in previous page) 3. Choose one of the available profiles and press ENTER. 4. Press BACK if you wish to return to Single Loop display without saving any changes.
Appendix A: Ramp Soak Running several profiles simultaneously To run several profiles simultaneously, follow these steps: 1. Setup the profiles so that segment 1 of each profile has the same latched trigger. 2. Assign the profiles to the appropriate loops. The loops will go to the Ready segment of each profile. 3. Set each profile to Run mode. 4. Trip the trigger.
Appendix A: Ramp Soak Bar graph display Loops that are running R/S profiles have different Bar Graph display codes. For these loops, you will see the first letter of each mode where the controller would normally display M (for Manual control) or A (for Automatic control). LOOP 1 PROCESS 2 3 4 5 UNITS 6 7 8 RMSMMMRS ALARM SETPOINT STATUS OUTPUT% The next table shows the codes you would see in loops running R/S profiles. Code Meaning R A profile is running. H A profile is holding.
Appendix A: Ramp Soak How many times has it cycled? From Single Loop display, press the RAMP/SOAK key twice. The next menu will appear. This menu displays the number of times the profile has run out of the total number of cycles. LOOP PROCESS UNITS 1A00/20S 1 2 3 4 5 6 7 8 CYC 1/1 ALARM SETPOINT STATUS OUTPUT% Holding a Profile or Continuing from Hold Use the profile mode menu to hold a profile or continue from Hold. The next table shows the available modes.
Appendix A: Ramp Soak Continuing a profile If a profile is holding and you want it to run, you can put it in Continue mode. • Press RAMP/SOAK key repeatedly until you see the R/S mode menu • While the profile is holding, the only mode you will be able select is Cont (Continue). • Press YES to continue the profile, and then ENTER to advance to the next menu. Resetting a profile Use this menu to reset a profile. When you reset a profile, the following happens: • The profile returns to the ready segment.
Appendix B: 8LS-CP Appendix B: 8LS-CP The 8LS-CP controller with a Zirconia Carbon Probe assembly can control and record the Dew point of atmosphere generators or the percentage of Carbon Potential of hardening and sintering furnaces. The 8LS-CP can accept direct connection of one to four Zirconia carbon probes without any special external signal conditioning amplifiers.
Appendix B: 8LS-CP System Configuration The 8LS-CP uses a modified input with discreet components per carbon input. Each CP input requires two loops. The 8LS-CP is factory configured to contain between 1 to 4 CP loops. The unit must be ordered for the number of CP inputs required per 8LS. Loops not used for the CP input may be used as standard inputs. The analog output of loops 7 and 8 can be used for recording analog process signal representing the PV of loops 2 and 4 (carbon probe inputs).
Appendix B: 8LS-CP The 8LS-CP is not only ordered for the number of carbon input loops desired, but the CPU DIP Switch on the CPU board must be set correctly to reflect the number of carbon inputs. Number of Carbon Loops CPU DIP Switch #7 #8 CP-1 Off Off CP-2 Off On CP-3 On Off CP-4 On On The figure below presents a typical 8LS-CP control system.
Appendix B: 8LS-CP Specifications The standard specifications listed in the Introduction section of this manual apply to the 8LS-CP with the following additions: Analog Inputs Each CP Input: • 1 Loop Selectable Type N, K, R, or S T/C Reference Temperature for CP • 1 Loop Selectable % Carbon Potential (CP), Dew point (DP), or DC MV • Carbon probe input Carbon Probe Input Range: • mV Range: 960 to 1275 mVdc • CP Range: .10 to 1.
Appendix B: 8LS-CP CP Control The temperature control may be accomplished by using a standard Analog Input/Output loop or it may be installed so that the T/C Reference Loop of the CP input is the temperature control for the system. A standard PID control and output function is available from the T/C Reference Loop. When using the Carbon Burn Off function, the T/C Reference Loop should not be used for temperature control.
Appendix B: 8LS-CP Recommended CP Trim Gas Alarm for Continuous Applications When using the 8LS-CP for controlling the gas atmosphere, it is required to prevent gas from being introduced by the control system until the temperature is above 1400ºF (760ºC). The 8LS-CP has a digital output for each carbon input that will be On or Low whenever the PV of the reference T/C input is between 1400 to 2400ºF. When the PV is below 1400ºF or above 2400ºF, the digital output will be Off or High.
Appendix B: 8LS-CP Carbon Probe In general practice, follow the probe manufacturer’s recommendations as to installation and maintenance schedule. General Guidelines 1. The probe must be exposed to the same atmosphere as the work load. 2. Be sure of the physical location as to length so the work load will not hit the probe and—for free atmosphere—flow around the probe. 3. Reference air flow should be in the range of .2-1.0 SCFH. Air flow below .2 SCFH will cause incorrect readings. 4.
Appendix B: 8LS-CP Probe Burn Off Carbon Probe Burn Off Requirements: 1. To burn off carbon, excess fresh air is supplied to the end of the probe. 2. The excess fresh air burning off the carbon will cause the temperature of the probe to increase. The temperature must be monitored from the probe internal T/C, so that the maximum temperature of the probe is not exceeded. 3. The excess fresh air flow requirement is 1 to 2 SCFH. 4.
Appendix B: 8LS-CP The figure below describes the typical installation of a carbon burn off system. Carbon probe 8LS-CP-1 T/C CP/DP PID control Burn off digital Input Burn off digital output SSR Optional for batch furnace Solenoid valve Air Enriching gas Batch furnace N.C. Solenoid valve Carbon control valve N.O Door open contact N.
Appendix B: 8LS-CP If you want to disable the enrichment gas during the burn off period, a Normally Open solenoid valve should be installed in the enriching gas line and powered from the same SSR that is supplying power to the burn off air solenoid valve. In both modes, the control output signal will be held an additional two minutes after the burn off period to allow the probe to stabilize before resuming automatic control.
Appendix B: 8LS-CP CO+CO2% and % of Hydrogen Upon selecting CP as the input type, the following menu is available. Use it to adjust the amount of CO+CO2% in the atmosphere. LOOP PROCESS 2 1 UNITS CO% 2 3 4 5 6 7 8 ?20 ALARM SETPOINT STATUS OUTPUT% Selectable Range: 1-30%. Upon selecting DP as the input type, the following menu is available. Use it to adjust the amount of Hydrogen in the atmosphere.
Appendix B: 8LS-CP Offset Calibration If the carbon probe input type is set to CP or DP, a menu is available for editing an offset calibration of the probe input in the engineering units of the process variable. The MV input is in direct reading of the millivolt output of the carbon probe with no offset adjustable available. LOOP PROCESS UNITS 2 OFFSET 1 2 3 4 ? ALARM 5 6 7 8 0 ºF SETPOINT STATUS OUTPUT% Selectable Range: Input Type Offset Range CP -.99 to +9.
Appendix B: 8LS-CP typically used in continuous furnace applications. Setting the start mode to Input means the burn off procedure will be started based on a digital input signal. This is typically used in batch furnace applications. LOOP PROCESS UNITS 2BO STRT 1 2 3 4 5 6 7 8 MD? OFF ALARM SETPOINT STATUS OUTPUT% Selectable Values: Off, Time, Input. Burn Off Time Interval This menu is displayed if the start mode is set to Time. Use it to edit the time interval between the burn off function.
Appendix B: 8LS-CP Burn Off Time Period This menu is displayed if the start mode is set to either Input or Time. Use it to edit the time period of the burn off. This is the time that the burn off air flow output will be set On to allow air flow to the probe burn off port. LOOP PROCESS UNITS 2BO TIME 1 2 3 4 5 6 7 8 MINS? 5 ALARM SETPOINT STATUS OUTPUT% Selectable Range: 1-45. Maximum Allowable Probe Temperature This menu is displayed if the start mode is set to either Input or Time.
Appendix B: 8LS-CP Setup Alarms CP Gas Alarm This menu is available from the Setup Alarms main menu. Use it to set the digital output number for the CP trim gas alarm output. This output is On when the temperature of the T/C Reference Loop is between 1400 to 2400ºF and Off when the temperature is outside these limits. When setting it to 0, the CP GAS output is disabled. LOOP PROCESS UNITS 2CP GAS 1 2 3 4 5 6 7 8 OUTPN? 0 ALARM SETPOINT STATUS OUTPUT% Selectable Range: 1-30, or 0.
Appendix B: 8LS-CP 120 8LS User’s Guide
Appendix C: 8LS Cascade Appendix C: 8LS Cascade Introduction The Cascade control feature allows the output percentage of one control loop to be used as the setpoint of a second control loop. The loop providing the output is called the Master or Primary loop. The loop that is using the output is called the Slave or Secondary loop. In Watlow Anafaze multiloop controllers, the Master loop output can supply more than one secondary setpoint loop with a cascade setpoint.
Appendix C: 8LS Cascade Choosing the Primary Loop Use this selection to choose the primary loop for cascade control. This loop provides the output for the Secondary loop, which is the current loop as it appears on the upper line of the display. LOOP Current loop Also the Secondary loop. PROCESS UNITS 1 SP? 1 2 3 4 5 6 7 8 OUTPUT 2 ALARM SETPOINT STATUS OUTPUT% Primary loop. This loop’s output will be the setpoint for the current loop.
Glossary A AC See Alternating Current. AC Line Frequency The frequency of the AC power line measured in Hertz (Hz), usually 50 or 60 Hz. Accuracy Closeness between the value indicated by a measuring instrument and a physical constant or known standards. Action The response of an output when the process variable is changed. See also Direct action, Reverse action. Address A numerical identifier for a controller when used in computer communications.
Glossary Bumpless Transfer A smooth transition from Auto (closed loop) to Manual (open loop) operation. The control output does not change during the transfer. C Calibration The comparison of a measuring device (an unknown) against an equal or better standard. Celsius (Centigrade) Formerly known as Centigrade. A temperature scale in which water freezes at 0°C and boils at 100°C at standard atmospheric pressure. The formula for conversion to the Fahrenheit scale is: °F=(1.8x°C)+32.
Glossary Derivative Control (D) The last term in the PID algorithm. Action that anticipated the rate of change of the process, and compensates to minimize overshoot and undershoot. Derivative control is an instantaneous change of the control output in the same direction as the proportional error. This is caused by a change in the process variable (PV) that decreases over the time of the derivative (TD). The TD is in units of seconds.
Glossary Filter Filters are used to handle various electrical noise problems. Digital Filter (DF) — A filter that allows the response of a system when inputs change unrealistically or too fast. Equivalent to a standard resistor-capacitor (RC) filter Digital Adaptive Filter — A filter that rejects high frequency input signal noise (noise spikes). Heat/Cool Output Filter — A filter that slows the change in the response of the heat or cool output.
Glossary Integral Control (I) Control action that automatically eliminates offset, or droop, between setpoint and actual process temperature. See Auto-reset. J Job A set of operating conditions for a process that can be stored and recalled in a controller’s memory. also called a Recipe. Junction The point where two dissimilar metal conductors join to forma thermocouple. Low Deviation Alarm Warns that the process is below the setpoint, but above the low process variable.
Glossary O Offset The difference in temperature between the setpoint and the actual process temperature. Offset is the error in the process variable that is typical of proportional-only control. On/Off Control A method of control that turns the output full on until setpoint is reached, and then off until the process error exceeds the hysteresis. Open Loop A control system with no sensory feedback. Operator Menus The menus accessible from the front panel of a controller.
Glossary Range The area between two limits in which a quantity or value is measured. It is usually described in terms of lower and upper limits. Recipe See Job. RTD See Resistance Temperature Detector. Reflection Compensation Mode A control feature that automatically corrects the reading from a sensor. Relay A switching device. Electromechanical Relay — A power switching device that completes or interrupts a circuit by physically moving electrical contacts into contact with each other.
Glossary Span The difference between the lower and upper limits of a range expressed in the same units as the range. Spread In heat/cool applications, the +/- difference between heat and cool. Also known as process deadband. See deadband. The transmitter acts as a variable resistor with respect to its input signal. Transmitters are desirable when long lead or extension wires produce unacceptable signal degradation. U Upscale Break Protection A form of break detection for burned-out thermocouples.
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