AST RESEARCH TECHNICAL BULLETIN TB-0131                  11-01-85


       COMPATIBILITY OF AST-5251/12 WITH HAYES 2400 BAUD MODEM


The Communications Department has completed testing of the Hayes 2400 
baud modem.  Our test showed that the Hayes modem will work with the 
AST-5251/12 as long as the modem is configured properly.

To accomplish this, you will first need to attach the modem to an 
asynchronous port, and then initialize it for 2400 baud with a 
communications software package.  After this has been accomplished, 
you will want to send a set of "AT" commands to the modem.

For the modem that will reside at the PC, the commands are as follows:

     AT&F................Sets modem to synchronous mode
     AT&M2...............Store Number Dial (Auto-Dial mode)
     AT&Z(Phone #).......Store telephone number
     AT&R0...............CTS tracks RTS
     ATS26=50............Sets RTS-CTS time delay
     ATQ1................Disables result codes back to the terminal
     ATE0................Inhibits Command Echo
     AT&W................Writes configuration to nonvolatile memory

This will set the modem to Synchronous Auto-Dial.  For the modem that 
will reside at the host, the commands are as follows:

     AT&F................Sets modem to synchronous mode
     ATS0=1..............Sets modem to Auto Answer
     AT&M3...............Manual dial through DTR control
     AT&R0...............CTS tracks RTS
     ATS26=50............Sets RTS-CTS time delay
     ATQ1................Disables result codes back to the terminal
     ATE0................Inhibits Command Echo
     AT&W................Writes configuration to nonvolatile memory

This will set the modem to Synchronous Auto-Answer.  After this has 
been accomplished and the modems are attached to the system, you would 
then bring up the AST-5251/12 package.  When the 5251/12 is brought 
up, it will cause DTR to rise and in turn the modem will start 
dialing.  When the two modems establish communications the squelch 
will stop and the 5251/12 will be on-line.