Omega Engineering OMB-NETSCAN, User Manual

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Appendix A API Command Reference
NetScan User’s Manual A-21
D# - Set Relay Make Time
TYPE
System
EXECUTION Deferred
SYNTAX D#make Specify how long to wait after closing a channel relay before reading valid
data, where make is the number of 520.833-microsecond intervals.
DESCRIPTION
The Set Relay Make Time ( D# ) command allows the user to increase the delay between closing a relay and
reading valid channel data. The system powerup default is: make = 6 = 3.125 milliseconds.
If common mode voltages on adjacent channels are widely dissimilar, reading inaccuracies can result. This
inaccuracy is due to inadequate settling time at the instrumentation amplifier when the unit is scanning between
channels. To eliminate these inaccuracies, the settling time can be increased using the
D# command as shown
in the example below.
EXAMPLE
PRINT#1, “M#0X” ‘ Select Normal mode
PRINT#1, “W#32X” ‘ Select number of samples = 32
PRINT#1, “D#12X” ‘ Set Relay Make Time = 12 = 6.25 milliseconds
PRINT#1, “Y0,10,0X” ‘ Setup to read 10 past trigger scans
PRINT#1, “C1-128,1X ‘ Enable channels 1 – 128 for J type thermocouples
PRINT#1, “T1,8,0,0X”
‘ Arm the unit
PRINT#1, “@X” ‘ Trigger unit and collect scans
E
- End Calibration Mode
TYPE Calibration
EXECUTION Immediate
SYNTAX E Terminate Calibration Mode
DESCRIPTION
Note: This command is only for advanced users who perform their own calibration. It is not necessary for
normal, everyday operation.
To use this command the unit must be in Calibration Mode. The End Calibration Mode ( E ) command is then
used to take the unit out of Calibration Mode. Once this command has been executed the unit will no longer be
in Calibration Mode and the Enter Calibration Mode command (
K ) must be issued to re-enter Calibration Mode.
Chapter 6, Calibration contains additional information.
EXAMPLE
PRINT#1, “K12345X” ‘ Enter Calibration Mode
‘ Apply precision voltage
PRINT#1, “H17X” ‘ Will calculate offsets for card #2
‘ Wait for command to complete
‘ Apply precision voltage of -50.0 mV
PRINT#1, “G17,1X” ‘ Calibrate negative gain for TC for card #2
‘Wait for command to complete
‘ Apply precision voltage of +50.0 mV
PRINT#1, “G17,1X” ‘ Calibrate positive gain for TC for card #2
‘ Wait for command to complete
‘ Apply temperature of 90.0 °C
PRINT#1, “J1,2,90.0X” ‘ Calibrate cold junction offset for channel 1 on card 1
‘ Wait for command to complete
‘ Remove precision voltage
PRINT#1, “EX” ‘ End Calibration Mode