How can I test to see if data is going through my serial tunnel?


A serial tunnel is formed by two Ethernet serial servers that transmit data received by the local serial port through a TCP/IP connection out through the remote serial port. Below are two simple methods for observing the traffic between the Ethernet serial servers.

  1. Perform an end-to-end loopback test. This tests the local serial server’s serial configuration and the network configuration of both serial servers.
    • Connect a loopback connector to the remote serial server.
    • Use a null modem connector to send data into the local serial port and examine the data echoed back to you.
    • In WinSSD, you can use the terminal, BERT, and loopback test applications. Please note that, in some cases, WinSSD’s BERT and terminal are more accurate than the loopback test.
  2. When data is being sent from the remote serial server to the local serial server, connect to the local unit’s serial port with a null modem adapter to examine the data stream coming out of the tunnel. In the WinSSD terminal, the “Hex/ASCII” option will let you easily examine the widest possible range of data formats.

These two tests require no network changes or specialized equipment.