Interfacing to 34401A

I recently got my 34401A bench meter out of storage, and wanted it working with my computer, something I hadn’t done for several years. I forgot to get my ‘official’ Agilent connection cable, but figured I could use my standard cables no problem.

This took a bit of effort to actually get working, so here is my notes on the issue:

  1. The required settings are 9600 Baud, 1 Start Bit, 2 Stop Bits, Hardware flow control. Hyperterminal never seemed to work, possibly because the 34401A uses full RTS/CTS + DTR/DSR flow control. I did however have success with the ‘Termite’ program with the following settings: Image
  2. Send the SYSTem:REMote command first, you should see a little ‘RMT’ appear on the 34401A VFD front panel. This indicates comms are working. Try a READ? command too; As an example see the following, blue is what I’ve sent and green is the meter responding: Image
  3. I first tried a small null-modem adapter + RS232 extension cable. You need to ensure your cable has all lines connected, since the 34401A uses full flow control. My null-modem adapter didn’t have lines 1 & 9 connected straight-through, as the 34401A manual says it should be. I figured it wouldn’t matter since it doesn’t claim to use them, and the rest of the lines were connected as required, but the meter didn’t respond to any commands. Using a null-modem cable which had line 9 connected straight-through, but not 1, seemed to work fine. So the hardware can be an issue!
  4. So far the Excel/Word Plug-In hasn’t worked for me. I know it did at one point, so still working on that, but I might end up just using Python or something instead anyway.

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