Specifications
Section 7. Measurement Instructions 
7-44 
Parameter 
& Data Type 
Enter 
 2049  Communication parameters. 
 2054  Set up receive filter. 
 2304  Transmit string and/or data to device (formatter/filter). 
 2305  Transmit bytes. 
Param1 
Param1 is the first parameter that should be passed on to the SIO4 for the 
selected Command. Refer to the SDM-SIO4 manual for details.
Param2 
Param2 is the second parameter that should be passed on to the SIO4 for the 
selected Command. Refer to the SDM-SIO4 manual for details.
ValuesPerRep 
The ValuesPerRep parameter is the number of values to be sent or received 
from each SIO4 each time this instruction is performed.
Mult, Offset 
These parameters are the multiplier and offset with which to scale the values 
received by the datalogger from the SIO4.
SW8A (Dest, Reps, SDMAddress, FunctOp, SW8AStartChan, Mult, Offset) 
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 
& 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 
The FunctOp is used to determine the result that will be returned by the 
SW8A. 
Constant 
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 










