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Using Port Monitoring Software for Troubleshooting

Some integrators who start with a working hard-wired application may find they are not successful when substituting the radios for the wired connection. The best troubleshooting approach is to isolate the problem. A good starting point is to ensure that the radios are functioning separately themselves by conducting a "Loopback" or range test. This is done apart from the user application to determine that the radios are addressed and communicating on the same channel and at the same baud rates. (See the "Quick Start Guide" under modems product page for directions on performing this range test).

Next, ensure that the interfacel settings match your devices. For example, if the device communicates at 9,600 bps, then set the radio to interface at this same baud rate. If the parity of the device is set to odd or even parity then the radio must also be set to match (see: Parity settings on module). More information about connecting to a PLC can be found here: Radio Modems and PLCs.

If the baud rate or parity is unknown, one troubleshooting tactic is to monitor the PC's communication port and record each process as data passes through. Many different port monitoring software applications exist to make this possible. Many of these programs available as freeware. We recommend PortMon, which is a Microsoft developed COM port monitoring tool.

Example COM Port Monitoring Screenshot

These programs run in the background of the PC's COM port and gives you the ability to record the individual processes of serial communication, including timing. We suggest performing two tests (running your application for 10-30 seconds with each one is usually sufficient).

  1. Run the monitoring software with your hardwired application to record how the data is passed in a successful, working system.
  2. Run the monitoring software with the radios connected to compare the two logs.

The com port monitoring software files will contain information about baud rates, packet size, data and timing. The files can be compared and differences may reveal the problem in the connection.

For assistance in understanding the data please feel free to contact the support department at Digi.

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