Instrument Control (GPIB, Serial, VISA, IVI)

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NI-488.2 Comctr, HP53181A. Only the *IDN? command works. MEAS:FREQ? hangs

HP53181A will not respond to any other command except *IDN? Any other command that returns data does not respond. I'm using the NI-488.2 Measurement and Automation explorer to enter the commands. Anyone know what I'm doing wrong? Thanks
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Message 1 of 6
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I don't think that's the correct syntax because channel information is missing. Try "MEAS:FREQ? (@1)" or "MEAS:FREQ? (@2)" to get a frequency measurement from either channel 1 or channel 2. There are both CVI and LabVIEW drivers available from the Instrument Driver Network so if you're doing development in either of these environments, you won't have to do any coding of instrument commands.
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Message 2 of 6
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Neither MEAS:FREQ? (@1) or MEAS:FREQ? (@2) will respond. The *IDN? command does. I'm entering these commands into the NI-488 Communicator. However, it appears that after I send either of the commands above, it will then not respond to the *IDN? until I stop and re-start the NI-488 Communicator.
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Message 3 of 6
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You might want to check the triggering configuration of the instrument. Is there a signal at the input? The instrument may not return a measurment unless there is a signal there that meets the trigger criteria. I don't have an instrument manual handy so I can't verify that. The instruments that are here are currently being used for production so I can't experiment right now either.
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Message 4 of 6
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That was it. It will not respond unless it has locked onto a signal. I guess I expected it to work just like my voltmeter. Thanks. My next question would be this: Is there a way to specify a timeout value. It takes about 10 or 15 seconds before the call returns if there is no response. I would like for it to return in 5 seconds if there is no reading to take. Are you aware of a command to change the timeout value?
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Message 5 of 6
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You can modify the VISA timeout value to anything you want. If you're still experimenting in MAX, select the Property Node (Write) and select the attribute Timeout Value. In LabVIEW, the VISA property node can be found on the Instrument I/O>VISA>VISA Advanced palette. This should enable the VISA Read to return much quicker. I'm not sure about stopping the measurement of the instrument. You could try sending the ABORT command.
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Message 6 of 6
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