VXI VT1422A - Manual (Page 261)

VT1422A Command Reference 259 Chapter 7
CALCulate
CALCulate
The Calculate subsystem allows post-processed temperature compensation to be done
for voltage readings of the on-board reference thermistor of the VT1586A and for E,
J, and T thermocouple types. These commands will normally not be used, instead,
the conversions will be done by the DSP on the VT1422A or by the VXIplug&play
driver (for VT1529B).
These commands may be chosen if using the VT1586A with the VT1529B and do
not have a PC fast enough to keep up with the real-time conversions done in the
VXIplug&play driver (hpe1422_readFifoPost_Q() call). In this case, program the
VT1422A to do voltage measurements, not temperature measurements, on the
reference thermistor, the thermistor’s excitation voltage and the thermocouple
channels, then use the CALCulate subsystem commands to perform the conversions
off-line.
Subsystem Syntax CALCulate
:TEMPerature
:THERmistor? <thr_volts>,<exc_volts>[,resistance]
:TCouple? <type>,<thr_temp>,<volt_array>
CALCulate:TEMPerature:THERmistor?
CALCulate:TEMPerature:THERmistor? <thr_volts>,<exc_volts>[,resistance]
calculates the temperature of the VT1586A reference thermistor from the voltage
measured across it, the excitation voltage applied and the sum of the resistor values
in the divider circuit (see Figure 5-5 on page 173 for the recommended circuit for
measuring the VT1586A reference thermistor using the VT1529B). The temperature
is returned in ºC.
This command is available with VXIplug&play driver revision A.01.09 or later
(revision A.01.06 or later of hpe1422_32.dll).
Parameters
Comments •
Returned Value: thermistor temperature in ºC. The data type is float32.
•
Related Commands: CALC:TEMP:TC?
•
Send with VXIplug&play Function: hpe1422_cmdReal64_Q(...)
Parameter
Name
Parameter
Type
Range of
Values
Default
Units
thr_volts numeric (float32) -16.0 to 16.0 volts
exc_volt numeric (float32) -15.99 to +15.99 volts
resistance numeric (float32) 1800 to 520,000
default value = 400,000
ohms