ETS-Lindgren 2090 Controller User Manual

Page 90

Using the GPIB Command Set with the Model 2090

Model 2090 Multi-Device Controller

The Output Queue is the buffer which holds information

to be returned over the GPIB when a read command is

performed. As long as there is information in the Output

Queue, the MAV (Message Available) bit of the Status

Byte Register will be set.

This symbol represents a logical OR of all of the input bits.

As long as any one of the input bits is TRUE, the output

will be TRUE. If all of the input bits are FALSE, the

output will be FALSE.

These symbols represent a logical AND of the bits of the

two registers. If a given bit from both registers is TRUE

then the corresponding output is TRUE. If either bit is

FALSE then the output is FALSE.

The following section of program code and subroutines

illustrates the use of the GPIB status reporting system to

detect a number of error conditions on a standard tower.

Note the use of subroutines to create modified versions of

the commands "ibrd" and "ibwrt" which handle the

generation of a service request. This concept can be

extended to provide subroutines which handle service

requests from any GPIB call. There are also subroutines

for handling basic functions of the Model 2090. By

breaking up the program in this manner it is possible to

handle any condition with ease while at the same time

reducing the size of the program code.

Revision G– P# 399199