Interrogate Timing - HP 8112A Operating, Programming And Servicing Manual

Interrogate Timing

After receiving an interrogate command, the HP 8 1 12A needs some
time until it is ready to send the response to the computer. If
the device is not yet ready, it will send the string NO MESSAGE
instead of the response. Should your computer be too fast for the
HP 8 1 1 2A, it will be necessary to force the computer to wait a few
hundred milli-seconds before reading the response after an interrogate
command.
The HP 81 12A needs time to interpret and implement the commands
which it receives. You need to allow for this in your controller
program. A summary of programming timings is given in Table 6- 1 .
Programming
6-21