Hi,
I have an issue when I try to use LabVIEW 2015 to talk to a Tektronix TBS 1052B oscilloscope using VISA (with a USB connection). In particular, I seem to be able to write commands (e.g. '*IDN?'), but 'VISA Read' always returns nothing, and without errors. I know that VISA Write is working because I am able to write in a LabVIEW 2015 VI and then successfully read using the VISA Test Panel.
What is most confusing to me is that the both the VISA Test Panel as well as an identical VI written in LabVIEW 8.5 both Write/Read perfectly fine. I've attached screenshots to show the two VI's, as well as a log from NI Trace.
LabVIEW 2015:
LabVIEW 8.5:
NI Trace log:
You can see that in 8.5 and in NI Trace, the read commands return 'TEKTRONIX, TBS 1052B...' while 2015 returns nothing. All give no errors.
Things I've tried:
- Playing with Termination Character. I thought that maybe 2015 VISA Read always immediately encountered a Termination Character '\n' and thus returns 0 bytes. I tried disabling the Termination Character in the Instr. Property Node before VISA Open, but this didn't change anything.
- Adding a delay before VISA Read. I tried up to a 2 second delay to give the oscilloscope time before the Read command, but this didn't change anything.
- Different version of NI-VISA. Both NI-VISA 17.0 and NI-VISA 15.0 give the same results. Note that LabVIEW 8.5 uses NI-VISA 4.4.
Anyone have suggestions? Another question: what are the differences in the LV8.5 VISA blocks and the LV2015 VISA blocks?
Thank you for the help 