Digi TS8 serial console server funkiness

Thu Mar 8 03:06:04 UTC 2012

> 
> Other issues I've noticed..cannot use arrow keys to search command
> buffer.

This is going to be a tougher one.  Might be a difference in character encoding. Here is the VT100 spec:

http://www.handshake.de/infobase/dfue/prgrmmer/t322.htm

*  ESC D             cursor down - at bottom of region, scroll up
*  ESC M             cursor up - at top of region, scroll down

...

Arrows      Standard       Applications     IBM Keypad
   Up        ESC [ A        ESC O A          Alt 9
  Down       ESC [ B        ESC O B          Alt 0
  Right      ESC [ C        ESC O C          Alt -
  Left       ESC [ D        ESC O D          Alt =

So you probably need to check your keyboard encoding.  It likely differs from VT100 escape sequences.

Also, if you have several devices connected to that terminal server, see if you have one that is spewing debug or other information out the console port. That one might be causing some buffer overrun situations or keeping the CPU busy so it loses characters.  Line noise can cause garbled data, too.  But I would try flow control first.  One thing I have seen before also is ground loops causing issues.  Some serial devices actually tie signal ground to chassis ground.  If you have a cable connecting two such devices and there is some ground potential difference, you can create a ground loop and introduce noise (and things like sparks, fire, blown fuses, etc.) if the ground potential difference is great enough between the two devices.