Commandline test to see if a serial connection is up

My Digi serial hub seems to be screwing up on me. So I want to write a 
simple script that tests the serial connection of all the servers that I 
manage. Here's my question:

Is there any way from commandline to send a carriage return to a console 
and see if I get some sort of response back? I can write a script to 
handle the details, but I just want to know if I can execute read/write 
commands to the "console" program from commandline so I can put it in a 
script.

- Steve