SDM-SW8A 8 Channel Switch Closure Module Revision: 7/10 MADE IN USA SDM - SW8A 8 CHANNEL SWITCH CLOSURE INPUT MODULE IN 8 5V IN 7 5V IN 6 5V IN 5 5V IN 4 5V IN 3 5V IN 2 5V IN 1 5V C1 OUT C1 IN C2 C3 12V TO DATALOGGER C o p y r i g h t © 1 9 8 7 - 2 0 1 0 C a m p b e l l S c i e n t i f i c , I n c .
Warranty and Assistance The SDM-SW8A SWITCH CLOSURE INPUT MODULE is warranted by Campbell Scientific, Inc. to be free from defects in materials and workmanship under normal use and service for twelve (12) months from date of shipment unless specified otherwise. Batteries have no warranty. Campbell Scientific, Inc.'s obligation under this warranty is limited to repairing or replacing (at Campbell Scientific, Inc.'s option) defective products.
SDM-SW8A Table of Contents PDF viewers note: These page numbers refer to the printed version of this document. Use the Adobe Acrobat® bookmarks tab for links to specific sections. 1. Function........................................................................1 2. Specifications ..............................................................2 3. Power Supply Considerations ....................................3 4. Connections .................................................................4 4.
SDM-SW8A Table of Contents List of Tables 1. 2. 3. 4. 5. 6. Datalogger to SDM-SW8A Connections................................................... 2 SDM-SW8A to SDM-SW8A Connections................................................ 3 Address Jumpers ........................................................................................ 5 Measurement Jumpers................................................................................ 6 Bit Period Values ....................................................
SDM-SW8A Switch Closure Input Module 1. Function The 8 channel SDM-SW8A Switch Closure Input Module (see Figure 1) measures up to 8 channels of switch closure or voltage pulse inputs. Each channel may be configured to read single-pole double-throw (SPDT) switch closure, single-pole single-throw (SPST) switch closure, or voltage pulse. Output options include counts, duty cycle, and state.
SDM-SW8A Switch Closure Input Module 2. Specifications Operating voltage: Current drain: Environmental: 12 VDC nominal (9.6 to 16) 3 mA quiescent, 6 mA active (max) -25 to +50oC, 0 to 90% RH, noncondensing Measurement types: Switch closure (SPDT, SPST) DC voltage pulse Input voltage threshold: From below 0.9 to above 4.
SDM-SW8A Switch Closure Input Module TABLE 2.
SDM-SW8A Switch Closure Input Module 4. Connections All connections to the datalogger, power supply, and other SW8As are made from terminals located under "TO DATALOGGER" on the SW8A (refer to Figure 1). Sensor connections are made at the remaining terminals. 4.1 Connections to Dataloggers and Other SW8As The CABLE5CBL or a similar cable is used to connect the SDM-SW8A to a datalogger. Connections between an SW8A and a datalogger are shown in Table 1. Connections to multiple SW8As are shown in Table 2.
SDM-SW8A Switch Closure Input Module TABLE 3. Address Jumpers Pins Address 1-8 2-7 3-6 4-5 00 c c c c 01 c c c nc 02 c c nc c 03 c c nc nc 10 c nc c c 11 c nc c nc 12 c nc nc c 13 c nc nc nc 20 nc c c c 21 nc c c nc 22 nc c nc c 23 nc c nc nc 30 nc nc c c 31 nc nc c nc 32 nc nc nc c 33 nc nc nc nc c = connected nc = not connected FIGURE 2.
SDM-SW8A Switch Closure Input Module 5.2 Measurement Jumpers Near each input channel is a jumper triplet used to configure the channel for the measurement type. The SDM-SW8A is shipped from the factory with each channel configured for DC Voltage pulse. An example of each configuration is illustrated in Figure 2. Table 4 shows jumper pins and the corresponding measurement type. TABLE 4. Measurement Jumpers Measurement Type Pins Jumpered SPDT Switch Closure 1 and 6 SPST Switch Cl. or Open Coll.
SDM-SW8A Switch Closure Input Module Parameter & Data Type FunctOp Constant StartChan Constant Mult, Offset Constant, Variable, Array, or Expression Enter The FunctOp is used to determine the result that will be returned by the SW8A. Numeric Function Code 0 Returns the state of the signal at the time the instruction is executed. A 0 is stored for low and a 1 is stored for high. 1 Returns the duty cycle of the signal. The result is the percentage of time the signal is high during the scan interval.
SDM-SW8A Switch Closure Input Module The syntax of this instruction is as follows: SDMSpeed (BitPeriod) The BitPeriod argument can be an integer or a variable. If the SDMSpeed instruction is not in the program, a default bit period is used. If 0 is used for the argument, the minimum allowable bit period is used. Table 5 shows the default, minimum allowable, and maximum bit period for each of our CRBasic dataloggers. TABLE 5.
SDM-SW8A Switch Closure Input Module 6.2 Edlog Programming Instruction 102, Table 6, is used to address and retrieve information from the SW8A. TABLE 6. Instruction 102 - SDM-SW8A NOTE Parameter Number Data Type Description 01: 2 Repetitions 02: 2 Module Address (00..33) 03: 2 Function Option (0=State, 1=Duty 2=Counts, 3=Signature) 04: 2 SDM-SW8A Starting Channel (1..
SDM-SW8A Switch Closure Input Module Parameter 4 specifies the first SW8A channel to be read (1..8). One or more sequential channels are read depending on the Reps. To optimize program efficiency, the sensors should be wired sequentially. Data are stored in sequential datalogger input locations, starting at the location specified in Parameter 5. The number of input locations consumed is equal to the number of Reps. The scaling multiplier and offset (Parameters 6 and 7) are applied to all readings.
SDM-SW8A Switch Closure Input Module 7.3 Watchdog Reset Any microprocessor may occasionally fail due to input transients or intermittent component failure (e.g., a bombed condition). The SW8A has a "watchdog" counter which resets the processor under such conditions. When functioning normally, the processor resets the watchdog counter. To transfer data between the datalogger and the SW8A, the datalogger drives the clock line, Control Port 2, high and low (refer to Theory of Operation, Section 9).
SDM-SW8A Switch Closure Input Module 'Program name: C:\Documents and Settings\nigel\My Documents\Customers\INBO\SDM-SW8A BOMB.
SDM-SW8A Switch Closure Input Module 8. Measurement Applications 8.1 SPDT Switch Closure Single-pole double-throw switches may be found on some flow or volume sensors such as Watt-hour and water meters. The positive throw is connected to the 5 V terminal located next to the input channel, providing a 5 V bias for the SW8A to discriminate between throws. Similarly, the negative throw is connected to a ground terminal (refer to Figure 2, SPDT wiring example).
SDM-SW8A Switch Closure Input Module width becomes a limitation at 70 Hz (0.35/0.005sec), or about 126 MPH. The SW8A's maximum input frequency and 5 ms minimum pulse width specifications are not a limitation given the 014A's maximum calibrated speed of 100 MPH. 8.3 DC Voltage Pulse Voltage pulse transitions from below 0.9 V to above 4.0V, not exceeding ±20V, with a minimum pulse width of 5ms, are counted accurately at any frequency less than or equal to 100 Hz. 8.
SDM-SW8A Switch Closure Input Module Signal Magnitude - The signal magnitude should range from 0 - 0.9 V low, to 4 - 5 V high, or the signal should be centered around 2.5 V with a minimum 8 V peak to peak magnitude. When the magnitude is 0 V to greater than 5 V, the wave form begins to distort, resulting in less accurate duty cycle information. 9. Theory of Operation The Switch Closure Input Module uses a 63705 microprocessor to sample the 8 ports and communicate with the datalogger.
SDM-SW8A Switch Closure Input Module 16
Appendix A. Edlog Program Example The Edlog program is an example only and is not meant to be used verbatim. In application, the concepts illustrated here are likely to be only fragments of a larger program. The example program reads all 8 ports of an SW8A which is set to address 00. It is read three times per scan, once each for State, Duty Cycle, and Count information. The scan rate is fixed at 1 second, with a 5 minute output of State, average Duty Cycle, and average Count.
Appendix A. Edlog Program Example FIGURE A-1. Example Program Flow Chart PROGRAM EXAMPLE Input Locations Used: 1:STATE #1 13:DUTY #5 2:STATE #2 14:DUTY #6 3:STATE #3 15:DUTY #7 4:STATE #4 16:DUTY #8 5:STATE #5 17:COUNT#1 6:STATE #6 18:COUNT #2 7:STATE #7 19:COUNT #3 8:STATE #8 20:COUNT #4 9:DUTY #1 21:COUNT #5 10:DUTY #2 22:COUNT #6 11:DUTY #3 23:COUNT #7 12:DUTY #4 24:COUNT #8 25:RESET CNT Output Arrays: ID = 105, 27 ELEMENTS ID = 112, 4 ELEMENTS 105, DAY, HRMN, STATE #1,... STATE #8, DUTY #1, ...
Appendix A. Edlog Program Example *Table 1 Programs 01: 1 Sec. execution interval 1: Do (P86) 1: 1 Call Subroutine 1 If SDM-SW8A was just programmed or its processor is bombed, set intermediate processing disable flag. 2: 1 If Flag/Port (P91) 1: 21 Do if flag 1 is low 2: 19 Set Intermed. Proc. Disable Flag High (Flag 9) 3: If X<=>F (P89) 1: 1 2: 4 3: 0 4: 19 X Loc state #1 < F Set high Flag 9 OUTPUT STATE AND AVERAGE DUTY CYCLE EVERY 5 MINUTES.
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