
Section 7. Measurement Instructions
Parameter
& Data Type
Enter
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
A multiplier and offset by which to scale the raw results of the measurement. See
the measurement description for the units of the raw result; a multiplier of one and an
offset of 0 are necessary to output in the raw units. For example, the TCDiff
instruction measures a thermocouple and outputs temperature in degrees C. A
multiplier of 1.8 and an offset of 32 will convert the temperature to degrees F.
SDMX50 (SDMAddress, Channel)
SDMX50 allows individual multiplexer switches to be activated independently
of the TDR100 Instruction.
SDMX50 is useful for selecting a particular probe to troubleshoot or to
determine the apparent cable length.
Because it is usually easy to hear the multiplexer(s) switch, the SDMX50
instruction is a convenient method to test the addressing and wiring of a level
of multiplexers: Program the datalogger to scan every few seconds with the
SDM address for the multiplexer(s) and channel 8. The Instruction always
starts with channel 1 and switches through the channels to get to the
programmed channel. Switching to channel 8 will cause the most prolonged
noise.
Remember each multiplexer level has a different SDM Address. Level 1
multiplexers should be set to the address 1 greater than the TDR100, Level 2
multiplexers should be set to the address 2 greater than the TDR100 and Level
3 multiplexers should be set to the address 3 greater than the TDR100. If the
SDMX50 multiplexers for a given level are connected and have their addresses
set correctly they should all switch at the same time.
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