VXI VT1422A - Manual (Page 308)

306 VT1422A Command Reference Chapter 7
MEASure
MEASure:VOLTage:UNSTrained?
MEASure:VOLTage:UNSTrained? (@<ch_list>) This command automatically
configures the VT1422A to measure the bridge output voltage at each channel in
<ch_list> and initiates a measurement scan. It averages 32 measurements for each
channel and the averaged values are stored for later use by the strain Engineering
Units conversion process on these channels. The strain bridges must be unstrained
during this time. The average of each channel’s reading is also sent to the FIFO buffer
to be viewed later if desired. The command returns a single value which is the number
of readings sent to the FIFO.
Note that this command executes a measurement scan without executing any
algorithms that might be defined.
The sequence of individual commands to approximate this operation is
TRIGger:COUNt 1
one time through scan list
ROUTe:SEQuence:DEFine (@<ch_list>)
input the list of channels to measure
SENSe:FUNCtion:VOLTage [<range>,](@<ch_list>) set measurement function to volts
SENSe:STRain:EXCitation:STATE ON,(@<ch_list>) turn on excitation supplies
SENSe:STRain:CONNect BRIDge,(@<ch_list>)
connect channel sense to bridge output
INIT
start measurement scan
SENSe:DATA:FIFO:COUNT?
query for number of readings in FIFO
enter statement here to return FIFO reading <count>
SENSe:DATA:FIFO:PART? <count>
read unstrained voltage readings from
the FIFO buffer
enter statement to for block data from FIFO
next the unstrained voltage values acquired above must be sent back to the VT1422A by
executing the following command once for each channel in <ch_list> above:
SENSe:STRain:UNSTrained <voltage_value>,(@channel)
Notes
1. Unlike the MEAS:VOLT:UNST? command, the individual command
sequence above cannot keep defined algorithms from running at INIT.
Since algorithms can place values into the FIFO buffer, it will be necessary to
determine which FIFO values are the excitation voltages.
2. Remember that the MEAS:VOLT:UNST? command also provides the
average of 32 measurements for each excitation value.
Parameters
Comments •
This command is only for use on channels measured with the VT1529A/B. If
executed on channels connected to other strain SCPs, a 3007 "Invalid signal
conditioning plug-on" error message will be generated.
Parameter
Name
Parameter
Type
Range of
Values
Default
Units
ch_list channel list (string) 10000 - 15731 none