National Instruments GPIB-PC - Manual (Page 95)

BASICA/QuickBASIC GPIB-PC Function Calls Section Four A
GPIB-PC User Manual 4A-20 ©National Instruments Corp.
BASICA/QuickBASIC BASICA/QuickBASIC
IBCMD 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.