HOW TO: Test and Troubleshoot a Portserver or Digi One family Serial Port - UNIX/Linux systems

Note:  Before attempting any of the three troubleshooting methods below, verify that you are using a Serial cable pinned specifically for Digi's RJ45 serial pinout. RJ45 serial cables that were pinned for other manufacturers' products will likely not be compatible with your Digi RJ45 serial ports.

1) Troubleshooting a Port with serial port set at dev=term

  1. Telnet or log in to the Portserver and type:
    #> set port ra=## dev=term
    #> set line ra=## baud=9600 csize=8 parity=N stopb=1
              (where ## is the port number you wish to test)
  2. Disconnect the Portserver from the network and power cycle it.
  3. Set a dumb Terminal (or terminal emulation program) for 9600 8-N-1 and attempt to login on the port.
If you can login from the Terminal as root, then the port is working.


2) Troubleshooting a Port remotely with RealPort

  1. Short TxD (transmit) to RxD (receive)
    Note:  A cross-tip screwdriver can be used to short the TxD and RxD pins of a DB9 or DB25 port, or simply twist the two middle wires together on an RJ45 or RJ12 plug inserted into an RJ45 port.
  2. disable ttya01 ttyA01 [disable the ports for login in your OS ]
  3. cat < /dev/ttya01 & [this example is for SCO Unix, the method]
  4. date > /dev/ttya01 [or your version of Unix may differ]
  5. cat /etc/termcap > /dev/ttya01
  6. kill 0
If the date appeared on the screen during step 4, the port is working.  The /etc/termcap file (step 5) tests the function of software flow control.


3)Troubleshooting a Port remotely without RealPort

  1. disable ttya01 ttyA01 [assuming realport is installed]
  2. Telnet to the IP address of the Portserver on TCP port 23 and send the following commands:
    set port dev=prn ra=## [## is the port number you wish to test]
    set flow ra=## [make sure that all hardware signals are off*]
  3. Telnet to the IP address of the Portserver on TCP port 2000 + physical port number (example: port 1 = TCP port 2001)
?You are now typing directly to whatever is attached to the serial port of the Portserver (or a loopback plug if one is installed).  If a terminal is connected to the Portserver, you should see what you type appear on the Terminal screen.  If a modem is connected, you should be able to send AT commands to your modem.

Additional diagnostic indicators of Serial Port function

An additional check which can be run is to press the front-panel right arrow button of a PortServer or Portserver II, until the number of the port in question is shown on the LEDs. While doing any of the tests outlined above, watch the signal lights to determine what is happening on the port. The same can be done with a Portserver TS or Digi One family product by viewing the WebUI --- Administration --- Device Information --- (click Port ##)
Last updated: May 20, 2019

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