Error Codes and Solutions Appendix B
NI-488.2 User Manual for Windows B-8 © National Instruments Corp.
EBUS (14)
EBUS results when certain GPIB bus errors occur during device functions. All device
functions send command bytes to perform addressing and other bus management.
Devices are expected to accept these command bytes within the time limit specified by
the default configuration or the ibtmo function. EBUS results if a timeout occurred
while sending these command bytes.
Solutions
Verify that the instrument is operating correctly.
Check for loose or faulty cabling or several powered-off instruments on the GPIB.
If the timeout period is too short for the driver to send command bytes, increase the
timeout period.
ESTB (15)
ESTB is reported only by the ibrsp function. ESTB indicates that one or more serial
poll status bytes received from automatic serial polls have been discarded because of a
lack of storage space. Several older status bytes are available; however, the oldest is
being returned by the ibrsp call.
Solutions
Call ibrsp more frequently to empty the queue.
Disable autopolling with the ibconfig function or the wibconf utility.
ESRQ (16)
ESRQ occurs only during the ibwait function or the WaitSRQ routine. ESRQ
indicates that a wait for RQS is not possible because the GPIB SRQ line is stuck on. This
situation can be caused by the following events:
Usually, a device unknown to the software is asserting SRQ. Because the software
does not know of this device, it can never serial poll the device and unassert SRQ.
A GPIB bus tester or similar equipment might be forcing the SRQ line to be asserted.
A cable problem might exist involving the SRQ line.