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Determining Instrument Communication

Use the * IDN? command to determine if the computer can communicate with the instrument. Send the

command using the Secondary GPIB address (i.e., Logical Address / 8) of the instrument. The following

IBASIC sends to command to an instrument at Logical Address 24 (Secondary GPIB address of 03)::

DIM A$[128] ! Dim variable for returned data

OUTPUT 80903;"* IDN?" ! Send *IDN? command to instrument at Logical Address 24

ENTER 80903;A$ ! Enter returned data

PRINT A$ ! Print returned data

Program Message Terminator

All command sequences must end with a proper program message terminator. This could be a Line Feed

(LF), a Line Feed with an EOI statement, or an EOI statement. Programs like BASIC/IBASIC, or the

functions/subroutines of the GPIB Command Library automatically provides a Line Feed at the end of an

OUTPUT or IOOUTPUTS statement, respectively. For the functions/subroutines of the Agilent Standard

Instrument Control Library (SICL), the program must supply the terminator.

Step 2: Reset Each Instrument at the Start of the Program

After a power-on occurs (i.e., mainframe is turned on), each instrument in the mainframe is fully reset.

Since after using an instrument, it may be in a different state than when first turned on. The only way to

reset to its power-on condition, is to go through the following three stages of reset.

1. Issue an IEEE 488 Interface Clear command. This command opens any handshaking between the

computer and all instruments on the bus selected by the GPIB Select Code. The following lists the

Interface Clear command for several languages:

ABORT < select code> - BASIC/IBASIC

IOABORT (< select code> ) - QuickBASIC using the GPIB Command Library

IOABORT (< select code> ) - C/C+ + using the GPIB Command Library

2. Issue an IEEE 488 (or GPIB) Selected Device Clear. This command terminates instrument activity

and clears input/output buffers to prepare to receive ASCI commands The following lists the

Interface Clear command for several languages:

CLEAR < GPIB address> - BASIC/IBASIC

IOCLEAR(< device_address> ) - C using the GPIB Command Library

iclear(< device_session_id> ) - using the Standard Instrument Control Library (SICL)

3. Reset all features of each instrument and wait for its completion, shown as follows using an

IBASIC program:

OUTPUT 80900;"* RST;*CLS;* ESE 0;* SRE 0;*OPC?"

ENTER 80900;A

The * CLS;* ESE 0 ;* SRE 0 resets the instrument status system that is defined by IEEE 488.2.

Debugging VXI SCPI Programs C-3

Agilent Technologies 75000 Series B User Manual

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