EXCELLENCE IN MAGNETICS AND CRYOGENICS AMI MODEL 286 LIQUID LEVEL CONTROLLER INSTALLATION, OPERATION, AND MAINTENANCE INSTRUCTIONS American Magnetics, Inc.
Declaration of Conformity Application of Council Directives: Low Voltage Directive 72/23/EEC EMC Directive 89/336/EEC Manufacturer’s Name: American Magnetics, Inc. Manufacturer’s Address: 112 Flint Road, P.O. Box 2509 Oak Ridge, TN 37831-2509 U.S.A.
Model 286 Liquid Level Controller Model 286 Configuration AMI Order Number:_____________________ Shipping Date:_________________________ Model 286 Serial #:______________________ Firmware Revision:_____________________ Input Power Requirements:___________________________________________________________ Calibration Passcode:____________________ Configuration Notes: _____________________________________________________________________________________ ______________________________________________________
Table of Contents 1 2 3 4 Introduction .............................................................................. 1 1.1 Model 286 Features................................................................... 1 1.2 Front Panel Layout ................................................................... 3 1.3 Rear Panel Layout..................................................................... 4 1.4 Model 286 Specifications @ 25 °C .......................................... 6 1.
Table of Contents 4.1.3 4.1.4 4.1.5 4.1.6 5 ii Select the Appropriate Units .......................................38 Configure the HI and LO Alarms ................................38 Configure the A SETPOINT and the B SETPOINT...39 Select the Controller Mode ..........................................40 4.2 Sensor Contamination .............................................................42 4.3 Menu Reference........................................................................43 4.3.
Table of Contents 5.5 6 Error Messages........................................................................ 82 5.5.1 Command Errors ......................................................... 82 5.5.2 Query Errors ................................................................ 84 5.5.3 Execution Errors.......................................................... 84 5.5.4 Device Errors ............................................................... 85 Service ...............................................
Table of Contents iv
Foreword Purpose and Scope This manual contains the operation and maintenance instructions for the American Magnetics, Inc. Model 286 Liquid Level Controller. The manual outlines the instructions for instrument use in typical system designs.
Foreword Applicable Hardware Applicable Hardware The Model 286 has been designed to operate with AMI Capacitance-Based Liquid Level Sensors. Operation with other sensors is not recommended and may void the warranty. General Precautions Cryogen Safety Personnel handling cryogenic liquids should be thoroughly instructed and trained as to the nature of the liquids. Training is essential to minimize accidental spilling.
Foreword Safety Summary 2. Do not apply heat. Loosen any clothing that may restrict circulation. Apply a sterile protective dressing to the affected area. 3. If the skin is blistered or there is any chance that the eyes have been affected, get the patient immediately to a physician for treatment. Containers of cryogenic liquids are self pressurizing (as the liquid boils off, vapor pressure increases). Hoses or lines used to transfer these liquids should never be sealed at both ends (i.e.
Foreword Safety Summary rupture disks, etc.) included in the cryostat and top plate assembly are necessary. Recommended Safety Equipment • First Aid kit • Fire extinguisher rated for class C fires • Leather gloves • Face shield • Signs to indicate that there are potentially dangerous cryogens in use in the area.
1 Introduction 1.1 Model 286 Features The American Magnetics, Inc. (AMI) Model 286 Liquid Level Controller is a microprocessor-based instrument designed to provide multiple sensor capacitance-based monitoring and control of liquid levels. In addition to the brief feature descriptions provided below, a detailed feature matrix is provided on page 54. 1.1.
Introduction Model 286 Features indicates liquid level and fill/loss rate. The current liquid level is updated and visible in many of the display modes used in configuring various settings of the instrument. The 4 x 4 keypad is provided for direct entry of values for setpoints, sensor length, and other functions. The keypad also provides a convenient menutype interface for configuring various instrument settings that require selection from a list of options. 1.1.
Introduction Front Panel Layout 1.2 Front Panel Layout 1 $Ch 1: Ch 2: POWER I O OFF 2 100.0 % 50.0 % 1: HI/LO 1: FILL AMI 2: HI/LO 2: FILL Model 286 HI LO A 1 2 3 B RATE FILL 4 5 6 ASN MODE MISC 7 8 9 CAL 0 UNITS ESC MENU OPTION ENTER .
Introduction Rear Panel Layout 1.3 Rear Panel Layout 1 2 COMMUNICATIONS 1 RS-232 J8 3 2 ! A B LINE VOLTAGE, EACH 2A MAX J5A C J5B (OSC REQ'D) D SENSOR INPUTS 4 7 4 (OSC REQ'D) LINE: 50-60 Hz, 4.
Introduction System Diagram FRONT PANEL $Ch 1: Ch 2: POWER 100.0 % 50.0 % AMI I O Model 286 OFF 1: HI/LO 1: FILL 2: HI/LO 2: FILL HI LO A 1 2 3 B RATE FILL 4 5 6 ASN MODE MISC 7 8 9 CAL 0 UNITS ESC SOLENOID-OPERATED FLOW VALVES (OPTIONAL) MENU OPTION ENTER . Liquid Level Controller MODEL 286 LIQUID LEVEL CONTROLLER REAR PANEL COMMUNICATIONS 1 ! A B 2 LINE VOLTAGE, EACH 2A MAX J5A C J5B (OSC REQ'D) D SENSOR INPUTS (OSC REQ'D) LINE: 50-60 Hz, 4.
Introduction Specifications 1.4 Model 286 Specifications @ 25 °C Level Measurements Resolution: Linearity: 0.1 %, 0.1 cm, or 0.1 in ± 0.1 % or 1 mm (whichever is greater) Operating Parameters HI, A, B, and LO Setpoints: HI/LO Alarm Relay Contact Ratings: Controller Outputs: 0 % to 100 % adjustable 30 VAC or 60 VDC, 10 VA (up to 0.5A maximum) — 20 V at 0.5 A to 60 V at 0.167 A (normally open, closed on alarm) AC line voltage at 2 A maximum each output Analog Outputs Integral Non-linearity: ± 0.
Introduction Controller Modes Description: Normal Mode 1.5 Controller Modes Description The Model 286 provides a unique feature in the availability of three modes for level control. The function of each mode is summarized below and a diagram is provided to help illustrate the function. The controller modes provide flexibility for solving a wide range of level control problems with a minimum of external hardware or logic. 1.5.
Introduction Controller Modes Description: Auto-Changeover Mode 1.5.2 Auto-Changeover Mode In auto-changeover mode, as illustrated in Figure 1-3, the Model 286 monitors and controls liquid level measured via Channel 1, and uses liquid supplied from two storage vessels. The A and B setpoints for Channel 1 function as the liquid level control band for the controlled dewar. The dual AC outputs control a fill valve for each of the two storage vessels. Channel 2 is unavailable in the auto-changeover mode.
Introduction Controller Modes Description: Pre-Cool Mode 1.5.3 Pre-Cool Mode The pre-cool mode, as illustrated in Figure 1-4, provides for cooling of a cryogen transfer line before opening the transfer line to the controlled dewar. The A and B setpoints for Channel 1 function as the liquid level control band for the controlled dewar. AC Output 1 controls a fill valve for the controlled dewar, while AC Output 2 controls a vent valve. Channel 2 is unavailable in the pre-cool mode.
Introduction Controller Modes Description: Pre-Cool Mode 10
2 Installation Warning Before energizing the instrument, the earth ground of the power receptacle must be verified to be at earth potential and able to carry the rated current of the power circuit. Using extension cords should be avoided; however, if one must be used, ensure the ground conductor is intact and capable of carrying the rated current.
Installation Installing the sensor 2.2 Rack Mounting the Instrument If the instrument has a rack mount chassis, follow the following procedure: a. Attach the rack mount adapter pieces to the instrument by first removing the four screws on the side of the instrument that attach the cover to the chassis. Attach the rack mount adapter pieces to the sides of the instrument by reinstalling the screws. b.
Installation Sensor cabling 2.4 Connecting the Oscillator Cables to the AMI Sensors For Model 286 inputs A and B, connect each sensor to the Model 286 using a supplied 6 foot RG-59/U coaxial cable. For Model 286 inputs C and D, an external AMI oscillator must be used (note that inputs A and B do not require an external oscillator). For each sensor to be connected to either input C or input D of the instrument, connect the sensor to the oscillator using a supplied 6 foot RG-59/U coaxial cable.
Installation Valve installation 2.6 Installing the Optional Solenoid-operated Fill Valves Install each solenoid-operated fill valve by connecting the valve power cable to the AC controller output receptacle on the rear panel of the instrument (refer to the rear panel layout illustrated on page 4). The standard AMI supplied valve has a 9/32 inch orifice and the input and output are tapped for 3/8 NPT.
Installation Verifying power requirements 2.7 Connecting to Optional Analog Outputs See paragraph A.1 on page 95 for connection details for the 4-20 mA analog output option. See paragraph A.2 on page 96 for connection details for the 0-10 VDC analog output option. 2.8 Connecting to Communication Options See paragraph 5.3.1 on page 70 instructions concerning connection to the serial communications options (RS-232 and RS-422). Paragraph A.3 on page 98 shows RS-232 cable wiring. Paragraph A.
Installation Verifying power requirements 16
3 Calibration The Model 286 Liquid Level Controller is typically calibrated at the factory for specific length sensors for use in specific target liquids. The calibration lengths and calibration liquids are listed on the configuration sheet supplied with this manual. If a factory calibration method utilized was approximate, the calibration length will be noted as an approximate value. 3.1 Calibration Concepts 3.1.
Calibration Effects of dieletric shifts Diel-1 (saturated liquid) 0.5 Diel-1 (saturated vapor) 0.45 0.4 0.35 Diel - 1 0.3 0.25 0.2 0.15 0.1 0.05 0 0 50 100 150 200 250 300 350 400 450 500 Pressure (psi) Figure 3-1. Dielectric vs. pressure for nitrogen under saturated conditions. To minimize the effects of shifts in the dielectric of the target liquid, perform a closed dewar calibration (see page 22) at the expected operating condition of the cryo-vessel.
Calibration Calibration Methods 3.2 Calibration Methods The most straightforward calibration method is the Open Dewar Calibration which requires the customer to have access to a filled dewar where the full active length of the sensor can be dipped. The Closed Dewar Calibration method can be performed in situations where it is not feasible for the customer to dip the sensor into an open dewar, such as situations where the target liquid is under pressure.
Calibration Calibration Methods START Instrument & sensor purchased together? Y Verify sensor specifications Verify calibration sticker on bottom of instrument Is factory calibration correct? Y N N Can Open Dewar Calibration be performed in target liquid? Y Can Open Dewar Calibration be performed in target liquid? Y** Is factory calibration Approximate? N Y N Perform Open Dewar Calibration N Can Closed Dewar Calibration be performed in target liquid? Y Y Can Closed Dewar Calibration be p
Calibration Open dewar calibration 3.2.1 Open Dewar Calibration The instrument should be energized with the sensor connected to the instrument directly or via the oscillator (see the system diagram on page 5), depending upon the selected sensor input. The user should also first review the Calibration Menu Reference section beginning on page 29. 1. Enter the calibration menu by using the passcode, and select the appropriate sensor input to calibrate as documented in paragraph 3.3.2 on page 30. 2.
Calibration Closed dewar calibration 3.2.2 Closed Dewar Calibration A calibration can be performed in a closed dewar system by monitoring the liquid level while transferring the target liquid to an initially empty (or near empty) dewar at a constant rate. In order to insure success with the closed dewar technique, it is necessary to prepare the instrument by presetting the calibration MIN and MAX points outside the estimated level range.
Calibration Closed dewar calibration 9. Calculate the factor Cadj using the following equation: L active C adj = 120 1 + ( ε – 1 ) --------------L total where Ltotal is the total sensor length in inches, Lactive is the active sensor length in inches, and ε is the dielectric constant of the target liquid. 10. Enter Cadj into the instrument by placing the instrument in the custom approximate calibration factor entry screen as documented in paragraph 3.3.4.2 on page 31.
Calibration Closed dewar calibration available, use the 4-20 mA current loop output or a digital communications option (if installed) to query the instrument for the liquid level at regular time intervals during the fill. If no remote monitoring or communication option is installed, the level display must be manually plotted vs. time during the fill. 7. Commence filling the dewar. While the sensor is cooling down, there may be a slow drift in the displayed liquid level.
Calibration Closed dewar calibration value entered for Cadj (see steps 4 and 5 of the presetting procedure) until the current liquid level display falls below 100%, and then continue the procedure; or 2) continue the liquid transfer until the liquid level is determined to be 100% by means other than feedback from the instrument and then pressing the MAX calibration pushbutton. 9.
Calibration Approximate calibration 3.2.3 Approximate Calibration This procedure is the least accurate form of calibration and should be used only when the aforementioned calibration procedures are not possible. The approximate calibration method can be used in cases where the sensor cannot be dipped into the target liquid, the full active length of the sensor cannot be dipped into an open dewar, or both.
Calibration Approximate calibration While the sensor is submerged at the maximum depth, press the MAX button as prompted by the display. When the calibration point has been accepted, the display will change to Entered and the Model 286 will beep once. 8. Measure the distance between the bottom hole of the sensor and the location of the liquid level noted during step 7. This measured length is Ldipped. 9.
Calibration Approximate calibration The Model 286 also provides preset approximate calibration factors for common cryogens relative to liquid nitrogen, with both at atmospheric pressure. The preset values may be selected in lieu of entering a custom factor if the full active length of the sensor is dipped (Ldipped = Lactive). Note In contrast to the AMI Model 185/186 instruments, the approximate calibration factor is retained in the Model 286 memory.
Calibration Calibration Menu Reference 3.3 Calibration Menu Reference The CAL menu provides screens for calibrating the four sensor inputs. It is important to understand that a calibration is fixed to a sensor input, regardless of how the sensor inputs are assigned to the four channels. Each sensor input can have up to four independent calibrations.
Calibration Calibration Menu Reference 3.3.1 CAL Menu and Passcode Entry The CAL menu is accessed by pressing the CAL key in the default display mode (see the Operations section for an introduction to keying data). The CAL menu first requires that the user enter the 4-digit calibration passcode recorded in the first page of this manual. Key in the calibration passcode and press ENTER.
Calibration Calibration Menu Reference 3.3.4 Select Calibration Sub-Menu If the Select option is chosen as documented in paragraph 3.3.3, then the operator is presented with the following menu selections. The ESC key can be used at any point to exit the sub-menu. 3.3.4.1 Select active calibration A: Select Active $1* 2* 3 4 The select active calibration menu allows the operator to select one of up to four previously performed calibrations as the “active” calibration.
Calibration Calibration Menu Reference b. 100% liquefied methane assumed for LNG. The intent of the approximate calibration factor is to provide the operator with a method to transform calibrations performed in an inexpensive and relatively safe liquid (such as liquid nitrogen) to a more expensive or hazardous liquid (such as liquid hydrogen). It is also useful for transforming partial length calibrations to the full active length for extremely long sensors.
Calibration Calibration Menu Reference Note Use the OPTION key to toggle the sign for the zero offset. Zero offsets must be entered in percent units. The UNITS key is inactive within the menu. The allowable range for the offset value is −100% to 100%. If the entered offset value is within the allowable range, but results in an overflow of the measuring circuits within the Model 286, then the instrument will beep once and revert to the previous value.
Calibration Calibration Menu Reference Toggle the units key before beginning entry (or after ESC from an entry in progress) to toggle the units. The active length must be entered. The active length corresponds to the physical distance measured between the desired MIN and MAX points of the sensor.
Calibration Calibration Menu Reference and it must be re-entered. The capacitance of the MAX point must be greater than the MIN point in order to perform level measurements. The MIN point corresponds to the 0% level and minimum capacitance. Press 7 to initiate the MIN measurement. The instrument will emit a short beep if the attempt is successful and the display will change to Entered. The MAX point corresponds to the 100% level and maximum capacitance. Press 8 to initiate the MAX measurement.
Calibration Calibration Menu Reference 36
4 Operation 4.1 Operational Guidelines This section describes the front panel display and keypad functions for the Model 286. In addition to the front panel operation, the remote communication port provides methods for performing the identical operations and acquiring the current state of the instrument. Refer to the Remote Interface section beginning on page 57 for more details regarding the communication functions. The Model 286 provides up to four level measurement channels, designated as 1 through 4.
Operation Sensor input assignment For a selected channel, in order to access the various menus for setting the alarms, setpoints, fill mode, etc. press a key while the default display is visible. Pressing a key while the default display is visible activates the associated menu display. For example, pressing the HI key while the default display is visible enters the HI menu. Press the ESC key to exit a menu and return to the default display.
Operation A/B setpoints a. When the measured liquid level exceeds the HI alarm, the HI/LO LED on the front panel is energized amber and a set of HI alarm contacts are closed on the J5A or J5B connectors on the rear panel (see the Appendix for the pinout). When the level reaches or falls below the HI alarm, the LED is extinguished and the relay contacts open. b.
Operation AC output control a. When the measured liquid level falls below the B setpoint, if the AC output is configured for AUTO operation, an auto-fill cycle will initiate and the respective AC output will be energized. b. When the measured liquid level reaches or exceeds the A setpoint, if the AC output is configured for AUTO operation, the auto-fill cycle will terminate and the AC output will be deenergized. Note The A setpoint must always be above the B setpoint for a given channel.
Operation Fill timeout b. ON: With ON selected in the FILL menu, the rear panel AC output for the channel will become energized, thereby initiating flow if the solenoid-operated fill valve is properly connected. The FILL LED on the front panel will energize, indicating the presence of power at the rear panel receptacle. The operator is solely responsible for terminating the fill flow. c.
Operation Sensor contamination The instrument is typically shipped from the factory with a zero setting for the fill timeouts. 4.2 Sensor Contamination To ensure proper instrument calibration and operation, care must be taken to ensure the sensor is kept free of contaminants and not subjected to any force which would physically distort the sensor. Water or other electrically conducting substances in the sensor will disturb the measured capacitance and the instrument’s response.
Operation Menu Reference 4.3 Menu Reference The two types of default displays are illustrated in Figures 4-2 and 4-3 below. The default displays provide: 1) the level measurement in the selected units for each pair of channels, or 2) the level measurement and a usage estimate in the selected units per minute for the selected channel. Use the MENU key to toggle between the two types of default displays. Use the OPTION key to cycle the channel selection. The cursor $ indicates the currently selected channel.
Operation Menu Reference 4.3.1.1 Entering Numerical Values A common method of entering values is used within menus requiring numerical entries. Once a menu is selected, the user starts an entry by pressing a digit or the decimal key. The display will begin a new entry and display a cursor _ as a prompt for the next digit or decimal entry. To accept the entered value, press the ENTER key.
Operation Menu Reference will also sound if enabled. When the level reaches or falls below the HI alarm, the LED is extinguished and the alarm contacts open. The HI alarm may be set between 0.1% to 100.0%, and must be greater than the LO alarm. The default setting is 90.0%. Setting the HI alarm to 100% effectively disables the alarm and all associated LED indication and alarm contacts. 4.3.3 LO Menu $Ch 1: Lo: 50.0 % 20.0 % Accessible by pressing the LO key.
Operation Menu Reference 4.3.5 B Menu $Ch 1: B: 50.0 % 40.0 % Accessible by pressing the B key. The “B” menu adjusts the B setpoint level in the selected units, which defines the lower limit of the automatic fill function control band. If the FILL mode is set to AUTO, the B setpoint functions as the lower limit of the level control band, and thereby initiates a fill cycle when the level falls below the setpoint. Ch 1 & 2 The B setpoint may be set between 0.0% to 100.
Operation Menu Reference 4.3.7.1 Fill Mode Ch 1: Fill Mode On Off $Auto This menu provides three options for the fill mode of the Model 286. Press the OPTION key to cycle between the three selections. The associated FILL LED for the selected channel indicates the energized or de-energized state of the AC output. On: Energizes the AC output receptacle. Off: De-energizes the AC output receptacle. Auto: 4.3.7.
Operation Menu Reference opened, and will be re-initiated on contact closure. This option is useful for applications where critical operations may require minimum external disturbances. If the None option is selected, the contact input will be ignored and the fill cycle will initiate and terminate normally. The default selection is None. 4.3.8 FILL Menu in Auto-Changeover Mode In the auto-changeover controller mode, the FILL menu provides four menu screens for Channel 1.
Operation Menu Reference 4.3.8.3 Empty Detection Empty Detection: Use? $Timeout Empty Detection: Use? $Contacts The empty detection menu allows the user to specify whether simple timeouts or the remote contact senses will be used to determine the availability of liquid from each storage vessel. If the Timeout option is selected, the Model 286 will use the changeover time as the maximum amount of time allowed for an auto-fill cycle to complete.
Operation Menu Reference A changeover time of zero is not allowed, since not specifying a timeout would fill from only one storage vessel indefinitely. The default setting is 10 minutes. 4.3.8.5 Fill Timeout Fill Timeout: 0.0 min If the contacts method of empty detection is selected, a fill timeout is still available as a failsafe backup to the contacts indication.
Operation Menu Reference 4.3.9.1 AC Output 1 AC Output 1: On Off $Auto Controls the state of AC Output 1. Press the OPTION key to cycle between the three selections. The 1:FILL LED indicates the energized or de-energized state. The Auto selection allows the Model 286 to manage the auto-fill cycle for the controlled dewar. 4.3.9.2 AC Output 2 AC Output 2: On Off $Auto Controls the state of AC Output 2, which is connected to the vent valve. Press the OPTION key to cycle between the three selections.
Operation Menu Reference 4.3.9.4 Pre-Cool Time Pre-Cool Time: 2.0 min The pre-cool time menu specifies the venting period at the beginning of each auto-fill cycle in the pre-cool mode. The vent valve connected to AC Output 2 remains open for the specified time, before the fill valve connected to AC Output 1 is opened to fill the controlled dewar. The pre-cool time may be set to up to 9,999.9 minutes. The default value is 2.0 minutes. A value of 0.0 minutes is not allowed.
Operation Menu Reference 4.3.10 ASN Menu The assign menu is accessible by pressing the ASN key. The menu provides two screens for assigning a sensor input to the selected channel, and specifying whether the HI and LO alarm contacts will be associated with Channels 1 and 2 or Channels 3 and 4. 4.3.10.1 Sensor Input Assign Ch 1: Assign $A B C D ø Assigns a sensor input to the selected channel. Use the OPTION key to select the desired sensor input.
Operation Menu Reference functions of each mode, refer to the discussion in paragraph 1.5 on page 7. A feature matrix is also provided in paragraph 4.4 on page 56. Note If the auto-changeover or pre-cool controller modes are selected, Channel 2 becomes unavailable for level measurements and is assigned a null input. Upon re-selecting the normal mode, reassignment of an input to Channel 2 is required.
Operation Menu Reference 4.3.12.2 Display Contrast Display Contrast 80% The display contrast menu provides for adjustment of the contrast of the LCD display from 0 to 100%. The default setting is 80%. Enter a numerical value and press the ENTER key to commit a change. 4.3.12.3 Serial Baud Rate Serial Baud Rate 4800 $9600 If a serial interface card is installed in the instrument, the above menu will be displayed for entry of the baud rate of the serial interface.
Operation Feature Matrix 4.4 Feature Matrix The feature matrix below summarizes the functions available for each channel for the three controller modes.
5 Remote Interface Reference The Model 286 provides the capability of supporting RS-232 or RS-422 compliant remote interfaces. Only one remote interface option may be installed. 5.1 SCPI Command Summary The following manual conventions are used for SCPI (Standard Commands for Programmable Instruments) syntax for the remote interface commands: • • • Braces { } enclose valid command string or value choices. A vertical bar | separates multiple choices.
Remote Interface Reference SCPI Command Summary Status System Commands and Queries (see page 72 for more information) *STB? *SRE *SRE? *CLS *ESR? *ESE *ESE? *OPC *OPC? {CH1|CH2|CH3|CH4}:STATus:ALARm:CONDition? {CH1|CH2|CH3|CH4}:STATus:ALARm:EVENt? {CH1|CH2|CH3|CH4}:STATus:ALARm:ENABle {CH1|CH2|CH3|CH4}:STATus:ALARm:ENABle? STATus:MEAS:CONDition? STATus:MEAS:EVENt? STATus:MEAS:ENABle STATus:MEAS:ENABle? Alarm Configuration Commands and Queries (se
Remote Interface Reference SCPI Command Summary Level and Usage Queries (see page 75 for more information) {CH1|CH2|CH3|CH4}:LEVel? {CH1|CH2|CH3|CH4}:USAGe? Fill Modes Control and Query Commands (see page 75 for more information) FILL:MODE {0|1|2} or {NORMAL|AUTOCH|PRECOOL} FILL:MODE? AUTOCH:FILL:EMPTY {0|1} or {TIMEOUT|CONTACTS} AUTOCH:FILL:EMPTY? {CH1|CH2}:FILL:STATE {0|1|2} or {OFF|ON|AUTO} {CH1|CH2|AUTOCH|PRECOOL}:FILL:TIMEout {CH1|CH2}:FILL:INHibit {0|1} or {NO|YES} {CH1|CH2}:FILL:STATE? {C
Remote Interface Reference SCPI Command Summary Calibration Commands and Queries (see page 79 for more information) CAL:UNLOCK {A|B|C|D}:CAL:LENgth , {A|B|C|D}:CAL:PERForm ,{MIN|MAX} {A|B|C|D}:CAL:ACTIVE {A|B|C|D}:CAL:APPROX , {A|B|C|D}:CAL:OFFSET , {A|B|C|D}:CAL:LENgth ? {A|B|C|D}:CAL:ACTIVE? {A|B|C|D}:CAL:APPROX ? {A|B|C|D}:CAL:OFFSET ? CAL:LOCK Remote Unit
Remote Interface Reference SCPI Introduction 5.2 Programming Overview The Model 286 conforms to the SCPI (Standard Commands for Programmable Instruments) IEEE standard. The SCPI standard is an ASCII-based specification designed to provide a consistent command structure for instruments from various manufacturers. The Model 286 also implements a status system for monitoring the state of the Model 286 through the Standard Event, Alarm, and Status Byte registers. 5.2.
62 2 3 LO Alarm RATE Alarm 2 3 4 6 7 6 7 <128> <64> <32> <16> <8> <4> <2> <1> EN <64> 5 6 Command Error Power On <32> 4 Execution Error Fill Expired Fill OPEN Contact RATE Alarm EN <128> <64> <32> <16> <8> <4> <2> <1> STATus:MEAS:EVENt? 7 6 5 4 3 2 1 0 EV EN "OR" STATus:MEAS:ENABle STATus:MEAS:ENABle? <128> <64> <32> <16> <8> <4> <2> <1> Figure 5-1. The Model 286 status system.
Remote Interface Reference SCPI Status System An enable register (or bitmask) defines which bits in an event register are reported to the Status Byte register group. An enable register can be both written and queried. The *CLS (clear status) command does not clear an enable register. To enable or disable bits in an enable register, write a decimal value which corresponds to the binary-weighted sum of the bits you wish reported to the Status Byte register. 5.2.2.
Remote Interface Reference SCPI Status System • • • • A *CLS command is executed. The Standard Event register is read (only bit 5 of the Status Byte register is cleared). The indicated condition no longer exists. The power is turned off and then back on. The Status Byte enable register is cleared when any of the following occurs: • • The *SRE 0 command is executed. The power is turned off and then back on. 5.2.2.
Remote Interface Reference SCPI Status System • • The Standard Event register is queried using the *ESR? command. The power is turned off and then back on (with the exception of the “Power On” bit). The Standard Event enable register is cleared when any of the following occurs: • • The *ESE 0 command is executed. The power is turned off and then back on. Table 5-2. Bit definitions for the Standard Event register.
Remote Interface Reference SCPI Status System Channel 1 Alarm Event enable register, write a binary-weighted decimal value using the CH1:STATus:ALARm:ENABle command. The bit definitions for the Alarm Condition and Event registers are identical and are provided in Table 5-3. The Alarm Condition registers are continually updated for each level measurement is available. The Alarm Event registers latch the occurrence of each alarm and the respective bit(s) remain set until cleared.
Remote Interface Reference SCPI Status System Table 5-3. Bit definitions for each of the Alarm Condition and Alarm Event registers. Bit Number 5.2.5 Decimal Value Definition 2 B Alarm 4 “B” alarm condition or event (CH1 and CH2 only). 3 LO Alarm 8 “LO” alarm condition or event. 4 RATE Alarm 16 “RATE” alarm condition or event. 5 FILL bit 32 The associated AC output is energized (CH1 and CH2 only).
Remote Interface Reference Command Handshaking The Measurement Event enable register is cleared when any of the following occurs: • • The STATus:MEAS:ENABle 0 command is executed. The power is turned off and then back on. Table 5-4. Bit definitions for each of the Measurement Condition and Measurement Event registers. Bit Number 5.2.6 Decimal Value Definition 0 No input for CH 1 1 No valid input signal for the sensor input assigned to Channel 1.
Remote Interface Reference RS-232/422 Configuration 5.2.6.1 Using the *OPC Command The *OPC command is executed within the normal command queue. Upon completed execution of the *OPC command, the “Operation Complete” bit (bit 0) of the Standard Event register will be set. If the operator has so configured the Standard Event and Status Byte enable registers, the *OPC command can generate a service request when execution completes (see Figure 5-1).
Remote Interface Reference RS-232/422 Configuration page 55 for illustration of the menu provided for configuring the baud rate of the Model 286 serial interface. The Comm Menu provides menus to configure the baud rate (the default is shown in bold). All additional parameters are fixed: • • • • • 5.3.
Remote Interface Reference System-Related Commands 5.3.3 Device Clear A device clear can be initiated through the serial interface by sending the (ASCII code 03) character. The status registers and the error queue are left unchanged when the device clear character is received. Device clear performs the following actions: • • The Model 286 serial output buffer is cleared. The Model 286 is prepared to accept a new command. 5.
Remote Interface Reference Status System Commands • SYSTem:ERRor? Queries the instrument’s error buffer. Up to 10 errors are stored in the instrument’s error buffer. Errors are retrieved in first-in-first-out (FIFO) order. The error buffer is cleared by the *CLS (clear status) command or when the power is cycled. Errors are also cleared as they are read. See page 82 for a complete description of the error buffer and messages. 5.4.
Remote Interface Reference Status System Commands *ESE 60; • *ESE? The *ESE? query returns a decimal sum which corresponds to the binaryweighted sum of the bits enabled by the last *ESE command. • *OPC Sets the “Operation Complete” bit (bit 0) of the Standard Event register when executed. See page 69 for a complete discussion. • *OPC? Returns “1” to the requesting interface when executed. See page 69 for more information.
Remote Interface Reference Alarm Configuration Commands and Queries • STATus:MEAS:ENABle Enables bits in an Measurement Event register to be reported in the “Measurement Event” bit (bit 7) of the Status Byte register. To enable bits, you must write a decimal which corresponds to the binaryweighted sum of the bits you wish to enable. Refer to Table 5-3 on page 66 for more information.
Remote Interface Reference Level and Usage Queries • {CH1|CH2|CH3|CH4}:ALARm:LO? Returns the LO alarm value for the selected channel in the presently selected remote units. • {CH1|CH2|CH3|CH4}:ALARm:RATE Sets the RATE alarm limit for the selected channel in the presently selected remote units per hour. The RATE alarm applies to both positive (fill) or negative (empty) usage rates.
Remote Interface Reference Level and Usage Queries • FILL:MODE? Returns the current controller mode. 0, ”NORMAL” is returned if the controller mode is normal. 1, ”AUTOCH” is returned if the controller mode is auto-changeover. 2, ”PRECOOL” is returned if the controller mode is pre-cool. • AUTOCH:FILL:EMPTY {0|1} or {TIMEOUT|CONTACTS} Selects the empty detection method for the auto-changeover mode. An argument of “0” or “TIMEOUT” selects the timeout method of empty detection.
Remote Interface Reference Level and Usage Queries • {CH1|CH2}:FILL:STATE? Returns the state of the selected AC output (CH1 prefix selects AC Output 1 and CH2 prefix selects AC Output 2) for all controller modes according to the table below: Table 5-5. Return characters and their meanings for the {CH1|CH2}:FILL:STATE? query. Return Characters • Meaning 0, “OFF” AC output is de-energized. 1, “ON” AC output is energized. 2, “AUTO_OFF” AC output is under automatic control but is deenergized.
Remote Interface Reference Level and Usage Queries • {CH1|CH2}:FILL:INHibit {0|1} or {NO|YES} For normal mode only: Selects whether the remote contact sense is used to inhibit the initiation of a auto-fill cycle. An argument of “0” or “NO” selects no fill inhibit function (i.e. any remote contact sense is ignored). An argument of “1” or “YES” activates the fill inhibit function based on the remote contact sense for the respective channel.
Remote Interface Reference Calibration Commands and Queries 5.4.7 Calibration Commands and Queries The calibration command provides the user with a method of remotely initiating a calibration and setting or querying for various instrument settings associated with the calibration function. The value indicates that a value of 1, 2, 3, or 4 should be specified to indicate which calibration is to be modified or queried of the four possible calibrations for each input.
Remote Interface Reference Remote Units Commands and Queries • {A|B|C|D}:CAL:APPROX , Sets the approximate calibration factor for the sensor input and calibration selection specified. • {A|B|C|D}:CAL:APPROX ? Returns the approximate calibration factor for the sensor input and calibration selection specified. • {A|B|C|D}:CAL:OFFSET , Sets the offset factor for the sensor input and calibration selection specified.
Remote Interface Reference Remote Units Commands and Queries • INches Sets the remote units to inches. • CM Sets the remote units to centimeters.
Remote Interface Reference Error Messages 5.5 Error Messages If an error occurs, the Model 286 will beep, load the internal error buffer with the error code and description, and set the appropriate bits in the standard event and status byte registers if enabled by the user. Error codes are returned with a negative three-digit integer, then a comma, and then a description enclosed in double quotes. Use the SYSTem:ERRor? query to retrieve the errors in first-in-first-out (FIFO) order.
Remote Interface Reference Error Messages • -103, "Non-boolean argument" The command required a parameter in the form of 0 or 1. No other form of the parameter is allowed. • -104, "Missing parameter" The command required at least one argument which was not found before the termination character(s). • -105, "Out of range" At least one of the parameter values received was out of the valid range.
Remote Interface Reference Error Messages 5.5.2 • Query Errors -201, "Unrecognized query" The query string sent (identified as a query by a ?) was not identified as valid. Check the query string for invalid characters or separators, syntax errors, or for errors in the mnemonics. Spaces are not allowed before or after colon separators. • -202, "Query interrupted" A new query was processed before the return string of a previous query had been completely transmitted to the host.
Remote Interface Reference Error Messages • -306, "No input signal" The selected channel is not currently receiving a proper signal from the connected oscillator and/or sensor. • -307, "Not channel feature" A command or query was sent to a channel that does not offer the specific feature requested. • -308, "Selection out of range" The user attempted to select an active calibration outside of the valid range of 1 to 4.
Remote Interface Reference Error Messages • -403, "Serial parity error" The number of data bits and/or the parity of the Model 286 and the host device are not identical. • -404, "Serial data overrun" The received buffer of the Model 286 was overrun. Decrease the baud rate.
6 Service The procedures in this section should only be performed by Qualified Service Personnel (QSP). 6.1 Model 286 Maintenance The Model 286 is designed and manufactured to provide years of reliable service. The only routine maintenance required is to keep the exterior surfaces of the instrument clean by gently wiping with a damp cloth moistened with a mild detergent. 6.
Service Troubleshooting Hints 9. Use only grounded-tip soldering irons. 6.2.1 The Model 286 does not appear to be energized with the power switch in the POWER (I) position. 1. Ensure that the Model 286 is energized from a power source of proper voltage. Warning If the instrument has been found to have been connected to an incorrect power source, return the instrument to AMI for evaluation to determine the extent of the damage.
Service Troubleshooting Hints d. Replace the fuse and securely fasten the instrument top cover. Reconnect the power-cord. 3. Verify the input voltage selector switch (S1) on the instrument’s printed circuit board is in the proper position for the available input power. For 100 to 120 VAC input “115V” should be visible in the switch window; for 200 to 240 VAC input “230V” should be visible in the switch window. Checking the input voltage selector requires removal of the top cover of the instrument.
Service Troubleshooting Hints sensor will again approach the correct reading of 0%. This condition can also be corrected immediately if liquid nitrogen is added to the cold trap freezing the residual moisture. This is a physical phenomenon and does not indicate any problem with your AMI level equipment. 6. Verify the sensor is free of contaminants and is not subject to any physical distortion.
Service Troubleshooting Hints 6.2.5 One of the Model 286 channels reads instead of displaying the level The display indicates that the input assigned to the channel has not been fully calibrated. For the input assigned to the channel, the MAX has been calibrated, but not the MIN. Check to make sure that the intended input (A, B, C or D) is assigned to the channel and that the intended calibration selection (1, 2, 3, or 4) is active.
Service Troubleshooting Hints c. If a fuse is open, replace it with a 2.5A IEC 127-2 Type F Sheet II 5x20mm fuse. d. Check your connected equipment for compliance with the output receptacle rating. Caution Installing fuses of incorrect values and ratings could result in damage to the instrument in the event of component failure. 2. Replace the fuse(s) if needed and securely fasten the instrument top cover. Reconnect the power-cord. 6.2.
Service Line Voltage Selection receptacle. Failure to do this could expose the user to high voltages and could result in life-threatening electrical shock. Caution The Model 286 instrument operates on 50-60 Hz power and may be configured for 100-120 or 200-240 VAC ±10%. The power requirements for each instrument are marked on the rear panel. Be sure the instrument’s power requirements match your power source prior to plugging in the line cord.
Service Return Authorization 94
Appendix A.1 4-20 mA Current Loop Option The 4-20 mA output utilizes pins 3 and 4 of connector J5A for Channel 1, and pins 3 and 4 of connector J5B of connector J5B for Channel 2. These are self-powered current loop outputs (they require no external power supply). Refer to the figure below for wiring details. The 4-20 mA output has a maximum compliance of 11.5 VDC. If the 4-20 mA option is installed for a given channel, the 0-10 VDC output for that channel is not available.
Appendix J5A and J5B connectors A.
Appendix J5A and J5B connectors The HI level and LO alarm contacts also provide positive indication of a power-off condition. With a power-off condition, both the HI and LO alarm contacts will be closed for a given channel, which is a state unique to the power-off condition. The following table provides the specifications for the HI and LO alarm relay contacts (pins 5, 6, 7 and 8): Max switching VA 10 VA Max switching voltage 30 VAC or 60 VDC Max switching current 0.5 A Max continuous current 1.
Appendix RS-232 connector A.3 RS-232 Connector (optional) Table A-1. PC (DB-25)-to-Model 286 connections for RS-232 operation. PC (DTE) DB-25 Pin Model 286 (DCE) DB-25 Pin DTE Function 2 2 TD 3 3 RD 4 4 RTS 5 5 CTS 6 6 DSR 7 7 GND 8 8 DCD 20 20 DTR 22 22 RI Table A-2. PC (DB-9)-to-Model 286 connections for RS-232 operation.
13X/18X INSTRUMENT SIGNAL GROUND (SHOWN FOR REFERENCE ONLY; CONNECTED TO INSTRUMENT RS-422 DRIVER/RECEIVER CIRCUIT GROUND) EARTH GROUND (SHOWN FOR REFERENCE ONLY; CONNECTED TO INSTRUMENT CHASSIS AND TO AC MAINS "EARTH" CONDUCTOR) TX+ (PIN 14) TX- (PIN 2) RX+ (PIN 16) RX- (PIN 3) RX- (PIN 21) TX+ (PIN 3) TX- (PIN16) EIA-530 DEVICE TWISTED PAIR TWISTED PAIR DB25 FEMALE RX+ (PIN 2) TXTX+ 1 14 2 15 3 16 4 17 5 18 6 19 7 20 8 21 9 22 10 23 11 24 12 25 13 EIA-530 CONNECTOR
Appendix RS-422 connector 100
Index A AC output warnings 14 AMI Internet e-mail address 93 AMI WWW address 93 applicable hardware ii approximate calibration factor 27 audible alarm 38, 54 auto-changeover mode AC outputs 48 changeover time 49 empty detection 49 fill timeout 50 auto-fill cycle 40, 48, 50 C CAL menu action 30 active 31 active length 34 approx cal factor 31 MIN/MAX entry 34 passcode 30 perform 33 sensor input select 30 zero offset factor 32 calibration approximate calibration 26 closed dewar calibration 22 method selection
Index L LED FILL 47, 48, 51 HI/LO 44, 45 line voltage input range, modifying 93 M maintenance 87 MAX 35 menus accessing 43 exiting 43, 44 mode selection 53 reference 43 screens 43 selecting options 44 method of measurement 17 MIN 35 modes auto-changeover 8 normal 7 pre-cool 9 S safety cryogens ii equipment iv legend iv selected channel 43 sensor connections 13 sensor contamination 42 sensor installation 12 sensor-to-channel assign 53 specifications 6 summary of features 56 system diagram 5 N normal mode
