SDM-SW8A 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, 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. A 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. A 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 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.

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