National Instruments NI-488.2 Benutzerhandbuch

© National Instruments Corporation

A quick way to convert your application to use per-thread NI-488.2 globals 
is to add the following 

#define

 lines at the top of your C file:

#define ibsta

ThreadIbsta()

#define iberr

ThreadIberr()

#define ibcnt

ThreadIbcnt()

#define ibcntl

ThreadIbcntl()

If you are using 

ibnotify

 in your application (refer to the 

 section of this chapter), the 

ibnotify

 callback 

is executed in a separate thread that is created by the NI-488.2 driver. Therefore, if your 
application makes NI-488.2 calls from the 

ibnotify

 callback function and makes 

NI-488.2 calls from other places, you must use the 

ThreadIbsta

, 

ThreadIberr

, 

ThreadIbcnt

, and 

ThreadIbcntl

 functions described in this section, instead of the 

per-process NI-488.2 globals.

The device-level traditional NI-488.2 calls are designed to perform all 
of the GPIB management for your application. However, the NI-488.2 
driver can handle bus management only when the GPIB interface is CIC 
(Controller-In-Charge). Only the CIC is able to send command bytes to the 
devices on the bus to perform device addressing or other bus management 
activities. 

If your GPIB interface is configured as the System Controller (default), 
it automatically makes itself the CIC by asserting the IFC line the first 
time you make a device-level call.

If the current CIC does not pass control, the NI-488.2 driver returns the 
ECIC error code to your application. If this happens, you could send 
a device-specific command requesting control for the GPIB interface. 
Then, use a board-level 

ibwait

 command to wait for CIC.