Campbell Manufacturing SDM
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1. NOILONALSNI 3 Bag 855418 zd ee oo se SDM SW8A 8 Channel Switch Closure Module Revision 7 07 CAMPBELL MADE IN USA 5 scientiric INC SDM SW8A 8 CHANNEL SWITCH CLOSURE INPUT MODULE TO DATALOGGER LJ v3 248 215 z 15 z Copyright 1987 2007 Campbell Scientific Inc 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 The customer shall assume all costs of removing reinstalling and shipping defective products to CAMPBELL SCIENTIFIC INC CAMPBELL SCIENTIFIC INC will return such products by surface carrier prepaid This warranty shall not apply to any CAMPBELL SCIENTIFIC INC products which have been subjected to modification misuse neglect accidents of nature or shipping damage This warranty is in lieu of all other warranties expressed or implied including warranties of merchantability or fitness for a particular purpose CAMPBELL SCIENTIFIC INC is not liable for special indirect incidental or consequential damages Products may not be returned without prior a2. 19 VED gt d B R Hoooooo amp an 1 100k CDM e ge OI v M E av Qoi 10 UFD s a 5 5 ey 586 Bho of s fo GE lt H lt Yn lt gt Av ce t ce LSU md 2 c m e uM x 2 e r B a gt C DO e I m gt I lt gt FIGURE 2 SDM SW8A Address and Port Configuration Jumpers with Sensor Wiring Examples SDM SWS8A 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 SWSA 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 and 6 SPST Switch Cl or Open Coll 2 and 5 Voltage Pulse 3and4 6 Datalogger Programming 6 1 CRBasic Programming The SW8A instruction is used to control the SDM SW8A Eight Channel Switch Closure module and store the results of its measurements to a variable array Parameter Enter amp Data Type Dest Variable or Array Reps Constant SDMAddress Constant The variable in which to store the results
3. readings Enter 1 for the multiplier if no scaling is desired If the SW8A does not respond 99999 is loaded into input locations Modules which do not respond when addressed by the datalogger are possibly wired or addressed incorrectly Verify that the address specified in Parameter 2 corresponds to the jumper setting and that all connections are correct and secure An example program for reading state duty cycle and counts of all 8 ports in a Module with an address of zero 0 is given in the Appendix SDM SW8A Switch Closure Input Module 7T Datalogger Program Details 7 1 Datalogger Scan Rate 7 2 First Scan The Module samples channel state every 2 ms and accumulates the information for duty cycle and counts Each channel has one 16 bit accumulator for duty cycle and one for counts The accumulators are reset when the datalogger requests information from the SW8A and when the count exceeds 65535 The datalogger scan rate must be frequent enough to avoid SW8A accumulator overflow Each Duty Cycle accumulator resets every 131 seconds 2 ms 65536 or roughly 2 minutes If Duty Cycle is requested the datalogger scan rate must be less than 131 seconds The rate at which Count accumulators are reset is input frequency dependent For example at a maximum input frequency of 100 Hz the datalogger must sample the SW8A at least every 655 seconds approximately 10 minutes or the accumulator for that channel resets and starts over aga
4. Reps 2 00 Address 3 0 Channel state s function 4 1 Chan 5 1 Loc state 1 6 1 Mult 7 0 Offset Appendix A Program Example 3 SDM SW8A P102 1 8 Reps 2 00 Address az Duty cycle function 4 1 Chan 5 9 Loc duty 1 6 1 Mult 7 0 Offset 4 SDM SW8A P102 1 8 Reps 2 00 Address 3 2 Counts function 4 1 Chan 5 17 Loc counts 1 6 1 Mult 7 0 Offset 5 End P95 6 End Table 3 A 5 Appendix A Program Example A 6 Campbell Scientific Companies Campbell Scientific Inc CSI 815 West 1800 North Logan Utah 84321 UNITED STATES www campbellsci com info campbellsci com Campbell Scientific Africa Pty Ltd CSAf PO Box 2450 Somerset West 7129 SOUTH AFRICA www csafrica co za cleroux csafrica co za Campbell Scientific Australia Pty Ltd CSA PO Box 444 Thuringowa Central QLD 4812 AUSTRALIA www campbellsci com au info campbellsci com au Campbell Scientific do Brazil Ltda CSB Rua Luisa Crapsi Orsi 15 Butanta 005543 000 Paulo SP BRAZIL www campbellsci com br suporte campbellsci com br Campbell Scientific Canada Corp CSC 11564 149th Street NW Edmonton Alberta TSM 1W7 CANADA www campbellsci ca dataloggers campbellsci ca Campbell Scientific Ltd CSL Campbell Park 80 Hathern Road Shepshed Loughborough LE12 9GX UNITED KINGDOM www campbellsci co uk sales campbellsci co uk Campbell Scientific Ltd France Minipar
5. assume two SW8As with addresses of 22 and 23 are connected and 12 Reps are requested Eight channels from the first SW8A and the first four channels from the next will be read Only one Function Option Parameter 3 may be specified per Instruction If all four functions are desired four Instructions must be entered in the datalogger program Function Option 0 provides the state of the signal at the time 102 is executed 1 or 0 corresponds to high or low states respectively Function Option 1 provides signal duty cycle The result is the percentage of time the signal is high during the sample interval Function Option 2 provides a count of the number of positive transitions of the signal Function Option 3 provides the signature of the SW8A PROM positive number signature indicates the PROM and RAM are good a zero 0 indicates bad PROM and a negative number indicates bad RAM Function Option 3 is not used but is helpful in debugging Only one Rep is required for Option 3 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
6. holds a high state 5 V When contact is made with the ground throw a low state is maintained 0 V Switch bounce may occur any number of times at a throw but until contact is made with the opposite throw a change in state will not occur The pole must make contact with the throw for 3 ms for a state change to occur Figure 3 illustrates a raw SPDT signal in relation to the signal conditioned by the SW8A ik a ra on FIGURE 3 SPDT Signal Conditioning by SDM SW8A NOTE The 5V output located next to each of the 8 input channels is for biasing in the SPDT measurement 200 Ohm resistor is in series to protect against accidental shorting to ground 10 SDM SW8A Switch Closure Input Module 8 2 SPST Switch Closure Single pole single throw switches are either open high state or connected to ground low state Typical SPST switches include contact closure reed switch anemometers tipping bucket rain gauges and open collectors semiconductor switches Many control devices utilize open collectors and provide terminals for monitoring the switch For all SW8A measurements the 100 Hz maximum input frequency and 5 ms pulse width specifications must be taken into consideration To illustrate consider the Met One 014A Cup Anemometer which is an SPST type sensor The 014A calibration is MPH 1 789 f 1 where MPH miles per hour f pulse frequency in Hz The 100 Hz maximum input frequency to the SW8A equat
7. several cycles As shown by the equations the error decreases with decreasing frequency 11 SDM SWS8A Switch Closure Input Module 50 Duty Cycle The worst case duty cycle measurement error for a 50 duty cycle at a given input frequency is ERROR Hz 0 4 where ERROR Actual Duty Cycle Measured Duty Cycle For example a 50 duty cycle at 10 Hz could be measured as 46 to 54 in the worst case Minimum Maximum The measurable minimum maximum duty cycle is defined by the 5 ms pulse width specification of the SW8A For example at a 10 Hz frequency the minimum and maximum duty cycle that can be measured is 5 and 95 respectively 0 005 0 100 100 The worst case duty cycle measurement error for the minimum maximum measurable duty cycle is ERROR Hz 0 3 For example the minimum measurable duty cycle for a 1 Hz signal is 0 5 The duty cycle measurement could range from 0 2 to 0 8 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 12 The Switch Closure Input Module uses a 63705 microprocessor to sample the 8 ports and communicate with the datalogger The processor is in a low power Wait mode except when interrupted An inter
8. A Example Program Flow Chart 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 The SW8A is addressed by the datalogger allowing multiple SW8As to be connected to one datalogger refer to Theory of Operation Section 9 Sixteen addresses are available but for most applications Campbell Scientific Inc recommends no more than 4 SW8As be connected to one datalogger If more SWS8As are required please consult Campbell Scientific s Marketing Department In October 1988 SDM SW8A was introduced Edlog Instruction 102 is used for communication with the SW8A CRBasic dataloggers use the SDMSWSA instruction Previous to October 1988 the SDM SWS no A was offered for use only with the CR10 utilizing CR10 Instruction 15 SDM SWSAs are not compatible with CR10s containing Instruction 15 and SDM SWSs are not compatible with CR10s containing Instruction 102 Contact Campbell Scientific s Marketing Department for update options if incompatibilities exist CAMPBELL MADE IN USA SCIENTIFIC ING SDM SWS8A 8 CHANNEL SWITCH CLOSURE INPUT MODULE O DATALOGGE
9. R N ES LO cO gt FRE gt ee Es 155 dee aS CY O h G Z T G Z TV G Z Th FIGURE 1 SDM SW8A Front Panel SDM SWS8A Switch Closure Input Module 2 Specifications Operating voltage 12 VDC nominal 9 6 to 16 Current drain 3 mA quiescent 6 mA active max Environmental 25 to 50 0 to 90 RH noncondensing Measurement types Switch closure SPDT SPST DC voltage pulse Input voltage threshold From below 0 9 to above 4 0 VDC 20 VDC max Maximum input frequency 100 Hz 5096 duty cycle Minimum input pulse width 5 ms high 5 ms low Maximum bounce time 3 ms open without counting Output options State duty cycle counts Max count port 65535 Internal sampling frequency 500 Hz Watchdog reset Yes Total length of connecting cables 20 feet Dimensions 0 9 H 6 2 L 2 7 W Weight 0 5 Ibs 0 23 kg Compatible dataloggers CR10 X CR800 CR850 CR1000 21X CR23X CR3000 CR5000 and CR7 TABLE 1 Datalogger to SDM SW8A Connections Datalogger CR1000 CR800 CR850 CR23X CR3000 SDM SWS8A CR7 CR10 X CR5000 21X 12 12 12V 12V 12 see Note 1 G G C3 C3 C3 SDM C3 C3 C2 C2 C2 SDM C2 C2 C1 IN Cl CI SDM CI Cl C1 OUT not used not used not used 1H see Note 2 see Note 2 see Note 2 see Note 2 SDM SW8A Switch Closure Input Module
10. TABLE 2 SDM SW8A to SDM SWSA Connections SDM SWSA that s connected to a CR10 X CR800 CR850 CR1000 CR23X CR3000 SDM SWSA that s SDM SW8A CR5000 or CR7 connected to a 21X 12 12 V 12 C3 C3 C3 C2 C2 C2 C1 IN C1 IN CLIN C1 OUT not used see Note 2 C1 OUT see Note 3 Notes 1 If using an auxiliary power supply instead of connecting the datalogger s 12 V or 12 terminal to the SW8A connect the power supply s positive wire to the SW8A s 12 terminal The power supply s ground wire connects to the SW8A s terminal along with the wire that connects to the datalogger s G or terminal 2 When using a CR10 X CR800 CR850 CR1000 CR23X CR3000 or a jumper wire is used to connect the IN to the OUT SDM SWS8As shipped after March 1 2006 include this jumper 3 If you re using a 21X and the SDM SWS8A was shipped after March 1 2006 remove the jumper connecting C1 IN to C1 OUT 3 Power Supply Considerations Due to the 3 mA continuous and 6 mA active current drain an auxiliary 12 VDC power supply is recommended for powering the SW8A in remote long term applications For some applications it may be convenient to use the datalogger supply to power the SW8A For long term applications where AC power is available or where a solar panel can be used for recharging the lead acid power supply available with Campbell Scientific Inc dataloggers could be used For short t
11. able 1 Programs 01 1 Sec execution interval 1 Do P86 1 1 Call Subroutine 1 If SDM SWSA was just programmed or its processor is bombed set intermediate processing disable flag 2 1 If Flag Port P9 21 Do if flag 1 is low 2 19 Set high Flag 9 3 If X lt gt F P89 1 1 X Loc state 1 2 4 lt 3 0 F 4 19 Set high Flag 9 OUTPUT STATE AND AVERAGE DUTY CYCLE EVERY 5 MINUTES 4 If time is P92 1 0 minutes into a 2 5 minute interval 3 10 Set high Flag 0 output 5 Real Time P77 1 110 Day Hour Minute 6 Sample P70 1 8 Reps 25 4 Loc state 1 7 Average P71 1 16 Reps 2 9 Loc duty 1 8 If Flag Port P91 1 19 Do if flag 9 is high 2 30 Then Do 9 If Flag Port P91 1 11 Do if flag 1 is high 2 30 Then Do To force a watchdog reset increment reset counter output time and number of resets and set flag 1 low A 3 Appendix A Program Example 4 10 86 1 1 Call Subroutine 1 11 Z Z 1 P32 1 25 Z Loc RESET 12 Do P86 1 10 Set high Flag 0 output 13 Real Time P77 1 110 Day Hour Minute 14 Sample P70 1 1 Reps 2 725 Loc RESET CNT 15 Do P86 1 21 Set low Flag 1 16 Else P94 17 Do P86 1 11 Set high Flag 1 18 End P95 19 End P95 20 End Table 1 3 Subroutines SUBROUTINE TO MEASURE SDM SW8A 1 Beginning of Subroutine P85 1 1 Subroutine Number 2 SDM SW8A P102 1 8
12. c du Verger Bat H 1 rue de Terre Neuve Les Ulis 91967 COURTABOEUF CEDEX FRANCE www campbellsci fr info campbellsci fr Campbell Scientific Spain S L Psg Font 14 local 8 08013 Barcelona SPAIN www campbellsci es info campbellsci es Please visit www campbellsci com to obtain contact information for your local US or International representative
13. e the raw results of the measurement See Constant the measurement description for the units of the raw result a multiplier of one and an Variable offset of 0 are necessary to output in the raw units For example the TCDiff Array or instruction measures a thermocouple and outputs temperature in degrees C A Expression multiplier of 1 8 and an offset of 32 will convert the temperature to degrees F 6 2 Edlog Programming Instruction 102 Table 5 is used to address and retrieve information from the SW8A TABLE 5 Instruction 102 SDM SW8A Parameter Data Number 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 8 05 4 Starting input location for results 06 FP Mult 07 FP Offset SDM SWS8A Switch Closure Input Module NOTE Instruction 102 is not contained in all CR10 or 21X PROMS To verify that the datalogger contains the Instruction enter 102 into a datalogger Programming Table If the Instruction is accepted the PROM contains the Instruction Repetitions Reps Parameter 1 specifies the number of SW8A channels to read Parameter 2 is the address of the first SW8A If more Reps are requested than exist in one module the datalogger automatically increments the address and continues to the next SW8A The address settings for the SW8As must be sequential For example
14. erm applications only the alkaline power supply available with Campbell Scientific Inc dataloggers could be used to power the SW8A If the 21X power supply is used to power the SW8A all low level analog measurements thermocouples pyranometers thermopiles etc must be made differentially This results from slight ground potentials created along the 21X analog terminal strip when the 12 V supply is used to power peripherals This limitation reduces the number of available analog input channels and may mandate an external supply for the SW8A SDM SWS8A Switch Closure Input Module 4 Connections 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 Connections between an SW8A and the CR10 and 21X dataloggers are shown in Table 1 Connections to multiple SW8As are shown in Table 2 CAUTION 1 The order in which connections are made is critical ALWAYS CONNECT GROUND FIRST followed by 12 V and then the Control Ports 2 The sum of all the cable lengths connecting SW8As or other SDM devices and a datalogger should not exceed 20 feet Lengths in excess of 20 feet may prevent communication 4 2 Sensor Connections Figure 2 shows the connections between the SW8A and compatible sensor types 5 Internal Jumpers Inside the SW8A j
15. es to 180 MPH The duty cycle of the 014A as measured by the SW8A is 35 A 5 ms pulse width becomes a limitation at 70 Hz 0 35 0 005sec or about 126 MPH The SWS8A 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 8 4 Duty Cycle 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 Duty cycle is not an exact measurement due to the SW8A input filtering and 2 ms sampling frequency Signal magnitude also affects duty cycle measurements Optimum duty cycle measurements result if an integral number of cycles are measured per datalogger scan interval and the scan interval is at least 1 second Input Filtering and Sample Frequency Error In a worst case analysis input filtering will distort the time that the signal is high by 2 5 ms If the input filtering is at worst case the 2 ms sampling frequency can create an error of 2 duty cycle samples on any measurable cycle Equations given below estimate the worst case duty cycle measurement error for a 5096 duty cycle and the minimum maximum measurable duty cycle for a given frequency The error limits are calculated assuming a sample interval of a single cycle The error may be significantly reduced by allowing the SW8A to measure duty cycle over
16. essed SW8A is present The 21X works similarly except the data from the SW8A is input to single ended analog channel 1 not Depending on the Command Reps and Channel information the module will shift out one or more bytes to the datalogger again using C2 as a clock driven by the datalogger The module shifts out each bit on the falling edge of the clock the datalogger reads each bit on the rising edge of the clock Each time an entire byte is transmitted to the datalogger the SW8A is interrupted and prepares to send the next byte if any When all requested bytes have been sent the SW8A disables its serial communication interface and waits for both C3 and C2 to be driven low by the datalogger When this happens the SW8A prepares again to start a new command cycle An important feature of the module is its watchdog counter The counter pulls the processor momentarily into reset if the count gets too high The counter counts the C2 clock transitions Under normal operating conditions the processor resets the counter If the processor is bombed it will not reset the counter As the datalogger makes requests of the Switch Closure Module the counter increments to the point where it resets the processor the module will then start operating correctly again 13 SDM SWS8A Switch Closure Input Module 14 Appendix A Program Example The Edlog program is an example only and is not meant to be used verbatim In application the co
17. in From the time power is applied the SW8A samples the state of all channels every 2 ms The first time the datalogger executes Instruction 102 and requests information the results represent the time period since the SW8A was powered up not the datalogger scan interval This problem may be avoided by ignoring the data from the first scan after the datalogger is compiled The example program see Appendix includes a routine which discards first scan data 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 The watchdog counts clock line transitions and if the count exceeds 64 the watchdog resets the SW8A processor Requesting State produces 16 clock transitions Duty Cycle and Count each produce 24 16 clock transitions per channel The length of time that the SW8A stays bombed before a watchdog reset occurs is a function of the datalogger scan rate and the amount of information requested from the Module For example if the datalogger scan rate is 10 minutes and 2 channels of counts are requested the SW8A may stay bombed for 20 minu
18. logger 6 6 1 CRBasic Programming 6 6 2 Edl g Programming ere fete io eee ee 7 7 Datalogger Program Details 9 7 1 Datalogger Scan Rate nee 9 7 27 First SCAD eet eorr e e etes qe t end 9 4 3 Watchdog Reset oe ee aO EE 9 8 Measurement Applications 10 8 1 SPDT Switch Closure sese nnne nenne 10 8 2 SPST Switch Closure n here cte recte deett 11 8 3 DC Voltage Pulse oe Ree e S 11 8 4 Duty Cycle e eth uq auca adius ias 11 9 Theory of Operation 12 Appendix A Program Example eus Logon A 1 SDM SW8A Table of Contents List of Tables 1 2 3 4 5 Datalogger to SDM SW8A Connections SDM SWS8A to SDM SW8A Connections Address JUmpers Measurement Jumpers essere nennen Instruction 102 SDM SWSASA essere List of Figures 1 2 3 SDM SWSA Front Panel eene SDM SW8A Address and Port Configuration Jumpers with Sensor Wiring Examples esee SPDT Signal Conditioning by SDM SW8A
19. nal timer interrupts the processor approximately every 2 milliseconds to sample the input ports At this time for each port the duty cycle accumulator is updated and the transition counter is incremented if the state represents a positive transition from the previous state C3 driven high by the datalogger also interrupts the SW8A The SW8A prepares to receive an 8 bit byte consisting of address in the most significant nibble and command in the least significant nibble with the least significant bit always a 1 from the datalogger The datalogger drives C2 as a clock line and C1 as a serial data out line The datalogger shifts out each bit LSB first on the falling edge of the clock the Switch Closure Module shifts in each bit on the rising edge of the clock When all 8 bits are received by the SW8A the SW8A is again interrupted by its serial communication interface If the address part of the byte received equals the jumpered address the SW8A executes the command part providing itis valid For Function Options 1 and 2 the module receives another byte containing Reps and Channel information from the datalogger For a valid address and command the SW8A prepares to return a code byte as acknowledgment to the datalogger Except for the 21X the datalogger switches C1 to an input and after 2 milliseconds clocks back the code byte from the SW8A If the code byte is correct the datalogger knows the SDM SW8A Switch Closure Input Module addr
20. ncepts 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 To prevent erroneous values from being included in Output Processing routines the datalogger s Intermediate Processing Disable Flag Flag 9 is set under the following two conditions 1 When the SWS8A is not responding If the processor is not responding a value of 99999 is detected in the first Location containing SW8A data and Flag 9 is set high The SW8A is accessed a second time to increment the watchdog counter to greater than 64 and force a watchdog reset refer to Section 7 3 A RESET COUNTER input location 25 RESET CNT is incremented and output with time to create a record of when and how many times the SW8A has been reset since the last datalogger compilation 2 When the current scan is the first scan after compiling the datalogger program If the datalogger program is compiled in the 0 Mode all Flags are set low following compilation To detect the first scan after the datalogger is compiled the state of user Flag 1 is checked If Flag 1 is low the Intermediate Disable Flag Flag 9 is set high to prevent the first readings from being included in subsequent Output Processing Ins
21. of the SW8A measurement The variable array for this parameter must be dimensioned to the number of Reps The number of channels that will be read on the SW8A If StartChan Reps 1 is greater than 8 measurement will continue on the next sequential SW8A In this instance the addresses of the SDM devices must be consecutive The address of the first SW8A with which to communicate Valid SDM addresses are 0 through 15 If the SDMTrigger instruction is used in the program address 15 should not be used If the Reps parameter used more channels than are available on the first SW8A the datalogger will increment the SDM address for each subsequent device that it communicates with SDM SW8A Switch Closure Input Module amp Data Type FunctOp The FunctOp is used to determine the result that will be returned by the Constant SW8A Numeric Function Code Returns the state of the signal at the time the instruction is executed A 0 is stored for low and a is stored for high Returns the duty cycle of the signal The result is the percentage of time the signal is high during the scan interval Returns a count of the number of positive transitions of the signal Returns a value indicating the condition of the module positive integer ROM and RAM are good negative value RAM is bad Zero ROM is bad Constant greater than 1 measurements will be made on sequential channels Mult Offset A multiplier and offset by which to scal
22. tes To avoid this undesirable time delay before resetting a trapping routine may be programmed into the datalogger to detect a bombed condition and immediately force a watchdog reset The trapping routine keys on the fact that 99999 is stored in input locations when the Module is bombed 99999 is also stored if the Module is incorrectly addressed or wired wrong When 99999 is detected the routine immediately SDM SWS8A Switch Closure Input Module forces a watchdog reset by addressing the Module and requesting sufficient information to cause a minimum of 65 clock line transitions Advantages to the trapping routine are e The bombed processor is detected before erroneous values 99999 are included in subsequent processing e processor may be reset sooner time of processor failure may be logged by the datalogger e Number of failures may be logged A trapping routine as described above is included in the example program in the Appendix 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 When contact is made to the positive throw SW8A circuitry
23. tructions Flag 1 is set high at the end of the first scan A flow chart of the example program is presented in Figure A 1 A 1 Appendix A Program Example START Y GOSUB 1 MEASURE SDM SW8A IF 1st SCAN DISABLE INTERMEDIATE PROCESSING SET FLAG 9 HIGH IF SDM SW8 IS BOMBED DISABLE INTERMEDIATE PROCESSING SET FLAG 9 HIGH IF TIME FOR OUTPUT SET OUTPUT FLAG HIGH Y OUTPUT PROCESSING INSTRUCTIONS START TRAPPING ROUTINE Y CHECK FOR SDM SW8A BOMBED AND OR FIRST SCAN CONDITION IS FLAG 9 HIGH NO YES CHECK FOR SDM SW8A BOMBED IS FLAG 1 SET HIGH NO YES SW8A RESET Y Force SDM SW8A Reset Gosub 1 Increment Counter Output Time and Counter Value Set Flag 1 Low ELSE FIRST SCAN Set Flag 1 High END END END TRAPPING ROUTINE FIGURE A 1 Example Program Flow Chart PROGRAM EXAMPLE Input Locations Used 1 STATE 1 2 STATE 2 3 STATE 3 4 STATE 4 S STATE 5 6 STATE 6 T STATE 7 8 STATE 8 9 DUTY 1 10 DUTY 2 11 DUTY 3 12 DUTY 4 13 DUTY 5 14 DUTY 6 15 DUTY 7 16 DUTY 8 17 COUNT 1 18 COUNT 2 19 COUNT 3 20 COUNT 4 21 COUNT 5 22 COUNT 6 23 COUNT 7 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 DUTY 8 COUNT 1 COUNT 8 112 DAY HRMN RESET COUNT A 2 Appendix A Program Example T
24. umpers must be set to configure the Module address and the channel measurement type for each channel Remove the two panel screws and lift the cover to access the jumpers Figure 2 shows jumper location 5 1 Address Jumpers Each module can have 1 of 16 addresses 00 to 33 Base 4 The address is factory set to 00 Figure 2 shows the location of the address jumper block Table 3 lists the jumper settings for each address SDM SW8A Switch Closure Input Module TABLE 3 Address Jumpers Pins Address 1 8 2 7 3 6 4 5 00 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 31 nc nc c nc 32 nc nc nc c 33 nc nc nc nc c connected not connected 0000000 OOOOOOL 0000000 B Jet g Lai Nel Ral m Tel m 705 5 Gee lt s 0000000 OOOOOOO OOOOOOO KIND OOOOOOOOOO00000000000 dl MR ena O O G O O miel oo 088 CO C14 7S
25. uthorization The following contact information is for US and International customers residing in countries served by Campbell Scientific Inc directly Affiliate companies handle repairs for customers within their territories Please visit www campbellsci com to determine which Campbell Scientific company serves your country To obtain a Returned Materials Authorization RMA contact CAMPBELL SCIENTIFIC INC phone 435 753 2342 After an applications engineer determines the nature of the problem an RMA number will be issued Please write this number clearly on the outside of the shipping container CAMPBELL SCIENTIFIC s shipping address is CAMPBELL SCIENTIFIC INC RMA 815 West 1800 North Logan Utah 84321 1784 CAMPBELL SCIENTIFIC INC does not accept collect calls 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 Ms EU m 1 2 Specifications oec eaae a daas 2 3 Power Supply Considerations 3 4 Connections de 4 4 1 Connections to Dataloggers and Other 8 5 4 4 2 Sensor Connections 4 5 Internal Jumpers a eene 4 5 1 Address Jumpers y Baek ee Ril eH 4 5 2 Measurement one ttes rre ette Re Sereno 6 6 Data
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