Measurement-computing GPIB-488 Manuel d'utilisateur télécharger pdf (Page 19)

Chapter 3 GPIB 488.1 Library Reference

Programming Reference Manual 3-6 GPIB-488

IBCAC

Makes the specified board the Active Controller.

Syntax

C ibcac (int board, int sync)

Parameters

board is an integer containing the board handle

sync specifies if the GPIB board is to take control synchronously or asynchronously. If sync

is 0, the GPIB board takes control asynchronously. Otherwise, it takes control synchronously

(immediately).

When the board takes control, the GPIB interface board asserts the ATN line. When taking

control synchronously, the board waits for any data transfer to be completed and then takes

control. Note that if synchronous take control is specified while an

ibrd or ibwrt operation

is in progress, the synchronous take control may not occur if a timeout or other error occurs

during the

ibrd/ibwrt.

In comparison, if the board is to take control asynchronously, it takes control immediately,

without waiting for any data transfers to be completed.

Returns

ibsta will contain a 16-bit status word as described in Appendix B, IBSTA.

iberr will contain an error code, if an error occurred. In particular, the ECIC error occurs if

the specified GPIB board cannot become an Active Controller.

Usage Notes

This routine is only used when doing board level I/O.

Example

GPIB board 1 takes control asynchronously.

C ibcac (brd1, 0);

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Measurement-computing GPIB-488 Manuel d'utilisateur Page 19