Ibcmd – National Instruments GPIB-PC User Manual

Page 95

BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

GPIB-PC User Manual

4A-20

©National Instruments Corp.

BASICA/QuickBASIC

IBCMD

Purpose:

Send commands from string

Format:

CALL IBCMD (BD%,CMD$)

Remarks:

BD%

specifies an interface board.

CMD$

contains the

commands to be sent over the GPIB.

The

IBCMD

function is used to transmit interface messages

(commands) over the GPIB. These commands, which are
listed in Appendix A, include device talk and listen
addresses, secondary addresses, serial and parallel poll
configuration messages, and device clear and trigger
instructions. The

IBCMD

function is also used to pass GPIB

control to another device. This function is NOT used to
transmit programming instructions to devices.
Programming instructions and other device-dependent
information are transmitted with the read and write
functions.

The

IBCMD

operation terminates on any of the following

events:

•

All commands are successfully transferred;

•

Error is detected;

•

Time limit is exceeded;

•

Take Control (TCT) command is sent; or

•

Interface Clear (IFC) message is received from the
System Controller (not the GPIB-PC).

After termination, the

IBCNT%

variable contains the

number of commands sent. A short count can occur on any
event but the first.

An ECIC error results if the GPIB-PC is not CIC. If it is not
Active Controller, it takes control and asserts ATN prior to
sending the command bytes. It remains Active Controller
afterward.