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6-62 Chapter 6: Programming
Model 801GC, 801GF & 801GX¥Rev. A
Controlling via the IEEE-488 Port
You do not need to do anything special on the 801G*
to use it’s IEEE-488 port. The default settings are
for the 801G* to be a talker/listener with an ad-
dress of 15.
All of the commands and queries shown at the end
of this chapter can be used over the port. This sec-
tion covers how the commands should be sent over
the GPIB bus. Information on additional commands
that can only be sent through the GPIB port is also
included in this section.
Input Buffer
Commands are sent to the 801G* in “program mes-
sages.” A program message consists of one or more
commands separated by a semicolon (;) followed by
a program message terminator. A program message
terminator is defined as the NL character (ASCII
10), or EOI sent with the last byte of the program
message. The 801G* will not parse any commands
received until a program message terminator is re-
ceived. All commands are executed sequentially, that
is, when a command is parsed it is allowed to finish
execution before the next command is parsed.
Since some commands may take longer to execute,
the 801G* has an input buffer. This input buffer is
255 characters long and can be written to by the
host controller while the 801G* is busy executing or
parsing previous messages. If the input buffer be-
comes full, the 801G* will hold off the controller
until there is room in the buffer. For this reason, a
program message cannot be longer than 255 charac-
ters including terminator.