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trying to connect MP730424 DMM with rs232 but get Timeout error

JeremieWerner

I am trying to remote control a DMM MP730424 from a computer with Windows 11. *IDN? gives a VI_ERROR_TMO: Timeout expired before operation completed.

the instrument port information show: baud 115200, parity None, stop bits 1, data bits 8. 

What is the expected EOL and termination character?

has anyone manage to control this device via RS232?

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  • 0

    I don't have this instrument, but here are some things to try.

    Perhaps the transmit and receive pins need swapping. Sometimes instruments require a cable (e.g. null modem cable) to attach to the usb-to-RS232 adapter.  Worth trying both straight and swapped.

    Also, presume the USB-to-RS232 adapter is functioning? You can check by unplugging from the instrument and shorting the transmit and receive pins and testing with serial terminal software (such as PuTTY).

    Also, might be worth checking the instrument config menu, in case the default isn't 115200 (user manuals can be incorrect).

    You should try all combinations of CR/LF and see which one responds to your *IDN? But make sure to power-cycle the instrument before each attempt, because an incorrect line termination leaves instrument software in a messed up state often.

    Also, you could try different PC software (to eliminate potential PC software issues), for instance pyvisa is good. Or just test with serial console software.

  • 0 in reply to shabaz

    Hi Shabaz, thanks a lot for the suggestions. 

    - null modem: I now tried this but didn't help

    - usb-to-rs232: I tried shorting the read and write pins and it works. tested with NI Max. 

    - instrument configs: I checked and they are 115200, None, stop bits 1, data bits 8. I have checked that the cables and the serial software are all using the same. 

    - I tried *IDN?\r, *IDN?\r\n, *IDN?\n, *IDN?. all gives a timeout error.

    - PC software: tried with NI Max and with pyvisa. 

    could the instrument be defective? how to test? 

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  • 0 in reply to shabaz

    Hi Shabaz, thanks a lot for the suggestions. 

    - null modem: I now tried this but didn't help

    - usb-to-rs232: I tried shorting the read and write pins and it works. tested with NI Max. 

    - instrument configs: I checked and they are 115200, None, stop bits 1, data bits 8. I have checked that the cables and the serial software are all using the same. 

    - I tried *IDN?\r, *IDN?\r\n, *IDN?\n, *IDN?. all gives a timeout error.

    - PC software: tried with NI Max and with pyvisa. 

    could the instrument be defective? how to test? 

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