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Keysight 34972A - “*OPC?” function stops working properly after AC measurement

Question asked by matowc on Sep 2, 2019
Latest reply on Sep 10, 2019 by matowc

I use 34972A + 34908A 40ch switch. For some reason "*OPC?" command (waiting for the operation to complete stops working after AC measurement request.

The measurment is still executed, but "*OPC?" command reply is sent immediately, does not wait for the actual end of the measurement. I know it, because when I introduce an additional time delay in my code, it works, but the delay must be long enough for the measurement to complete.

It works great while measuring DC. Then I switch to AC and measure with the same MUX channel. First trial is OK, the second as well, but the next ones are not.

Below there is a dump from Wireshark:

DC

SENS:FUNC "VOLT:DC", (@222)

ROUT:SCAN (@222)

ROUT:CHAN:DEL:AUTO ON

TRIG:SOUR IMM

*OPC?

DATA:POIN?

No Error +1\n

DATA:REM? 1

No Error -2.54063640E+01\n

AC first trial

SENS:FUNC "VOLT:AC", (@222)

ROUT:SCAN (@222)

ROUT:CHAN:DEL:AUTO ON

TRIG:SOUR IMM

*OPC?

DATA:POIN?

No Error +1\n

DATA:REM? 1

+2.78389330E+01\n

AC second trial

SENS:FUNC "VOLT:AC", (@222)

ROUT:SCAN (@222)

ROUT:CHAN:DEL:AUTO ON

TRIG:SOUR IMM

*OPC?

DATA:POIN?

No Error +1\n

DATA:REM? 1

No Error +2.78847200E+01\n

AC third trial

SENS:FUNC "VOLT:AC", (@222)

ROUT:SCAN (@222)

ROUT:CHAN:DEL:AUTO ON

TRIG:SOUR IMM

*OPC?

DATA:POIN?

No Error +0\n

In the last case, if I have waited long enough before sending DATA:POIN?, it would return +1. However, that means that *OPC? does not work as it should

 

Help, please 

 

Full Wireshark dump: https://i.stack.imgur.com/a4oam.png 

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