Specifications

Section 7. Measurement Instructions
Parameter
& Data Type
Enter
Dest
Variable or
Array
The variable in which to store the results of the SW8A measurement. The
variable array for this parameter must be dimensioned to the number of
Reps.
Reps
Constant
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.
SDMAddress
Constant
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.
FunctOp
Constant
The FunctOp is used to determine the result that will be returned by the
SW8A.
Numeric
Code
Function
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.
2 Returns a count of the number of positive transitions of the
signal.
3 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
StartChan
Constant
The first channel that should be read on the SW8A. If the Reps parameter is
greater than 1, measurements will be made on sequential channels.
Mult, Offset
Constant,
Variable,
Array, or
Expression
The Mult and Offset parameters are each a constant, variable, array, or
expression by which to scale the results of the measurement.
SDMTrigger
When SDMTrigger is executed, the CR3000 sends a "measure now" group
trigger to all connected SDM devices. SDM stands for Synchronous Device
for Measurement. SDM devices make measurements independently and send
the results back to the datalogger serially. The SDMTrigger instruction allows
the CR3000 to synchronize when the measurements are made. Subsequent
Instructions communicate with the SDM devices to collect the measurement
results. Not all SDM devices support the group trigger; check the manual on
the device for more information.
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