What might cause a COM port violation when trying to connect from a computer to a TDR100 using PC-TDR software?

There are several possible things that should be considered or verified:

  1. Verify that there is 12 V dc on the TDR100 green connector. A reading between approximately 10 V to 16 V dc is OK.
  2. Use a standard RS-232 serial cable to connect from the PC 9-pin RS-232 communications port to the TDR100.
  3. Verify that PC-TDR is set up for the correct PC communication port. To do this, enter the PC_Com_Port in PC-TDR/Settings/Communication/Com_Port=??User specific??.
    • Note: Keep the baud rate set at 57.6.
  4. Verify that the TDR.ini file is set for the correct COM port. To do this when PC-TDR is closed, use a tool such as Windows Notepad to view/edit the TDR.ini file on a PC.
    • Example:
      1. The PC’s USB to RS-232 adapter is displayed as COM7 in PC-TDR.
      2. Close PC-TDR.
      3. In the C:\Campbellsci\PCTR\TDR.ini file, change the CommPtEx=1 line to CommPtEx=7.
    • Note: When a PC does not have a 9-pin RS-232 communications port, consider using pn 17394, USB-to-9-Pin Male RS-232 Cable.
  5. If there are still communication issues, make sure that other software packages (such as PC200W, PC400, and LoggerNet) that use the PC_Com_Port are closed when running PC-TDR. Otherwise, these software packages will be in conflict over access to the PC_Com_Port.
    1. Close PC-TDR.
    2. Cycle power on/off to the TDR100.
    3. Open PC-TDR.
    4. Verify Com_Port=??User specific??.
      • Note: Keep the baud rate set at 57.6.
    5. Either click PC-TDR Get Waveform or Water Content.

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