Friday, 1 February 2013

Serial Port Woes

The project to move the server to run on a Raspberry Pi has ground to a halt.  I need two serial ports, one for collecting CLI information from the phone line, and more importantly, one for PICNET.  Using USB-Serial adaptors I have been experiencing lockups and crashes, there would appear to be a problem somewhere in the USB driver stack.  I have tried various models of USB adaptor but so far they all seem to experience the same problem.

Unfortunately I have been busy with other activities so I haven't been able to investigate in greater depth yet.  So far I've determined that my server software continues to run after these lockups, recording in its log file that the PICNET network has gone down and also recording loss of communications to the display client and all the ETHPIC nodes.  (The ethernet port on the Pi hangs off the USB system.)   So it would appear that the USB system has locked up in some way.

As a quick test I set up a level shifter for the on-board serial port and used that for PICNET and it worked fine.  I added a USB Serial adaptor, but didn't tell the Polly server to use it, and still there were no problems and a test run of ten days was completed.  Finally, without rebooting or changing anything else I configured the CLI function in the server software to use the USB adaptor, and within a few hours everything was locked up again, despite the fact that there had been no phone calls so presumably no serial data to transfer.  This same configuration - "real" serial port for PICNET and USB adaptor for CLI has been used on the previous server PC for years without difficulties.

So I think it's time to trawl the internet to see if anyone else is having problems.