Serial Port Error Handling; Gpib Read And Write Termination Method - National Instruments GPIB-MAC User Manual

November 1985

Serial Port Error Handling

The GPIB-MAC continuously monitors the serial port for transmis-
sion errors. If it encounters an error in the serial data, the GPIB-
MAC records the error. You can program the GPIB-MAC to stop
processing the programming message when a serial port error
occurs or to ignore these serial port errors. Refer to the
function.
GPIB Read and'write Termination Method (END
and EOS)
You program the GPIB-MAC to Talk in order to send data messages
over the GPIB, and to Listen in order to receive data messages from
the GPIB.
The IEEE-488 specification defines two ways that GPIB Talkers
and Listeners may identify the last byte of data messages: END and
EOS. The two methods permit a Talker to send data messages of
any length without the Listener(s) knowing in advance the number
of bytes in the transmission.
* END message the Talker asserts the EOI (End or Identify)
* EOS character the Talker sends an EOS (end-of-string)
The two methods can be used individually or in combination. It is
important that the Listener be configured to detect the end of a
transmission.
21 SECTION THREE - PROGRAMMING THE GPIB-MAC
signal while the last data byte is being
transmitted. The Listener stops reading when
it detects a data byte accompanied by EOI.
character at the end of its data suing. The
Listener stops receiving data when it detects
the EOS character. Either a 'I-bit ASCII
character or a full g-bit binary byte may be
used.
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