Simple test environment:

1) Start device simulation:
   terminal.tcl &
   Or set up a real device.
   
2) Start ioc:
   xterm -e test.cmd &
   Or edit test.cmd first.
   
3) Start medm:
   medm -x -macro P=TEST test.adl &
      
Records:
TEST:cmd    - writes string to device
TEST:info   - writes string and reads reply (result in same record)
TEST:spy    - gets any input line from device
TEST:spybin - gets any input (binary waveform)
TEST:log*   - history of TEST:spy

Try to write 'help' to TEST:cmd.