Typical device library calls are 488.1 'ibrsp' and 488.2 'ReadStatusByte'.
6-7
USING 488.2 GPIB
The IEEE 488.1 GPIB standard was updated in 1987 to 488.2 to better enforce
standardization of GPIB communication. This section explains the fundamentals
of 488.2 GPIB operation and how it is implemented in the ML2430A Series Power
Meter. Refer to the full IEEE 488.2 standard for more detailed information.
488.2 Command
Format
All commands should follow the basic format:
<MNEMONIC><white space><comma separated message parameters><terminator>
<white space> = Normally a space character, but can be any of the white
space characters listed in the 488.2 manual.
<terminator> = A line feed character (for example, \n in ‘C’ or VBLF in Vis
-
ual Basic). An EOI ( End Of transmission Interrupt ) can be used as the
last character instead of the line feed.
Example: AVG A,MOV,64
A number of commands can be put into one program message by separating the
commands with semicolons. Example:
CHCFG 1,A;CHCFG 2,B-A;CHUNIT 1,W;CHUNIT 2,DBM;OPMD DIGIT
Status Byte The 488.2 standard added two extra predefined bits to the status byte, these bits
are the Event Status Bit (ESB) and the Message AVailable bit (MAV).
Event Status Bit
(ESB)
In 488.2 there is an event status register (ESR) that allows the
state of the GPIB interface to be monitored. All the bits in this regis
-
ter are defined. These bits are:
Event Status Register (ESR)
PON
Power On bit. This bit is set on power up of the device only.
URQ
Not used in the ML2430A Series
CMD
Command error. Received an illegal command.
EXE
Execution error. Could not execute a command. For example, a parameter is
out of the allowable range, or requesting graph data while in readout mode.
DDE
Device Dependent Error. The specific error can be found by using the ERRLST
command.
QYE
Query Error.
RQC
Request Control. GPIB controllers only.
ML2430A OM 6-7
GPIB OPERATION USING 488.2 GPIB
