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5 IEEE-488 Communication Option
The IEEE-488 communication option provides a GPIB connector on the rear panel of
the instrument for IEEE-488 (GPIB, HPIB) communications.
Command/return termination characters
All commands are transmitted and received as ASCII values and are case insensitive.
The Model 186 always transmits <LF> and EOI as the termination for return data. The
Model 186 can accept
<CR>, <LF>, <CR><LF>, <LF><CR>,
or
<LF>
with EIO
as termination characters from an external IEEE-488 interface.
Only one command at a time should be sent to the Model 186 by the external
IEEE-488 interface. Additional commands separated by a semicolon will not be
processed. The instrument uses a single 16 character buffer for input and output.
Consequently, all input strings including terminations should not be longer than 16
characters. Any excess characters will be discarded. All alphabetical characters are
case insensitive and character encoding is in accordance with IEEE 488.2.
Communicating with the Model 186
The use of a single buffer for both input and output is a result of memory limitations in
the Model 186. In order to keep the external IEEE-488 interface from sending
successive commands faster than the Model 186 can respond, the Model 186 uses the
Serial Poll Service Request (SRQ) to let the external computer know it has finished
processing the last command received and is ready to send a response. This is true of
all commands. Thus sending commands to the Model 186 using IEEE-488 protocol is
a three step process: 1) send the ASCII command, 2) wait for SRQ, and 3) get the
instrument response.
Note
API’s for some manufacturer’s cards require you to use different functions to
check for SRQ and read the serial poll status (spoll) byte. Invoking the
command to read the spoll byte may be required to actually clear the SRQ
status.
A basic flow diagram for sending an ASCII command to the Model 186 and receiving
a response is shown on the following page.
Summary of Contents for 186
Page 3: ...2 Introduction ...
Page 13: ...12 Installation Configuring power ...
Page 23: ...22 Calibration Approximate Calibration ...
Page 29: ...28 Operation Sensor contamination ...
Page 37: ...36 RS 232 Communication Data Logger Option Error Codes ...
Page 47: ...46 IEEE 488 Communication Option Serial Poll Status Byte ...
Page 55: ...54 Virtual Instrument Operation Running multiple GPIB devices ...
Page 65: ...64 Index ...