GPIB OPERATION | USING 488.2 GPIB |
| Typical device library calls are 488.1 'ibrsp' and 488.2 'ReadStatusByte'. |
| 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. |
488.2Command All commands should follow the basic format:
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
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 BitIn 488.2 there is an event status register (ESR) that allows the
(ESB) 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. |
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URQ | Not used in the ML2430A Series |
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CMD | Command error. Received an illegal command. |
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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. |
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DDE | Device Dependent Error. The specific error can be found by using the ERRLST |
| command. |
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QYE | Query Error. |
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RQC | Request Control. GPIB controllers only. |
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ML2430A OM | |
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