Forgive me if this is a simple problem, however I am not very experienced in this area.

I have two machines (server A and server B) connected using a serial cable. Server A writes to its serial port, which is then read by server A. The messages are very simple, and usually consist of a single word, or a couple of words separated by '|'.

This was all working fine, until a couple of days ago, when it suddenly stopped working. I've tried running this command on Server A:

And tried to watch the serial port on server B using:

However, nothing is coming from server A and arriving on server B.

Where can I start in order to fix this problem?

Thanks in advance

When trying to resolve serial communications problems, I always turn to C-Kermit first. It is a tool built for performing serial communications, and allows access to the serial ports in any possible configuration. It has decent reporting of status and error conditions. It allows you to interactively configure the ports, and see responses. A simple test is to loopback the Tx pin onto the Rx pin (pins 2 & 3 normally), and test for keystrokes echoing back. This can be done on each host independently to test the hardware and cabling. Further diagnostics can proceed from there. Another useful tool for this kind of job is an RS-232 breakout box. These used to be avaialable from Black Box, but I haven't bought one for a long time.

--- rod.