Here is some information on how instruments can communication to the IRTF TCS systems.

How can I communcation between my instrument and the TCS?

   The network communication are fairly simpled:

   A socket is opened to a program called the tcsd.
   A 160 char text string is send by the client.
   The client reads a 160 char text string from the socket.
   The socket is closed.

   This makefile and tcsio.c program that implements the client
   communications. tcsio should be easily compiled on any UNIX. It uses
   the BSD socket library.

   tcsio talks to 'stefan' or the 'tcsd_host'. You would need to add the following
   entries in your host table:

      128.171.165.6   stefan tcsd_host

   You can compiling tcsio on your system. Your instrument
   then can execute this as an OS command. For example, this
   execute from the shell prompt would command our tcs into the A beam.

   > tcsio ABEAM

   This command obtain some tcs position and time information:

   > tcsio 0 TPD
     07:24:31.19  19:49:34.0  00:00:00.00 1.000    0.0 -OK

Where can I get a copy of the commands supported by the IRTF TCS?

   Here are electronic copies of "Computer to TCS ASCII Communications".

   tcs1_comlink.pdf
   tcs1_comlink.ps

How does the spex guider send corrections to the TCS during its Slow Guide mode?

 Offsets should be >= 0.1 arsec as the TCS cannot accept values less than 0.1 arcseconds.

 After spex caculates the desired RA, Dec offset, the following code is used to form the
 command to be transmitted to the tcs:

   sprintf( buf, "0 %2.1f %2.1f 0 C.PEAK", ra, dec );
   tcs_com( buf, NULL, 0, tcshostname );

 For details on the C.PEAK, please review the "Computer to TCS ASCII Communication" document.