Much of the following text is derived from the NI-488.2 User Manual for Windows (see Additional Resources).
Error Condition: GPIB interface is locked and cannot be accessed.
Possible Cause: This error usually occurs when there are two or more processes that want to access the same interface and one process has already locked the interface. This error is returned when the operation cannot be performed because of the existing lock on the interface. It is also returned when a process tries to unlock an interface when no such lock exists.
Solution:
Error Condition: ibnotify callback failed to rearm.
Possible Cause: This error occurs when we use asynchronous notification (ibnotify) in NI-488.2 applications. This function is useful if you want your application to be notified asynchronously about the occurrence of one or more GPIB events. This event notification is carried out by means of a callback function. The callback function is registered with the NI-488.2 driver when the ibnotify call is made. This error indicates that this callback notification failed to rearm itself by returning an illegal value or when a fatal driver error (EDVR) has occurred.
Solutions:
Error Condition: Input Handle is invalid.
Possible Cause: Several GPIB commands take in the input handle of the board or the device as an input parameter which can be the source of this error. This error can occur under several circumstances. Some scenarios are listed below:
Solutions:
Error Condition: Wait In progress on specified Input handle.
Possible Cause: This error occurs in scenarios that have more than one thread in the same process and when two or more threads are accessing the same interface. EWIP indicates that an ibwait call is already in progress on the specified unit descriptor and it occurs when a thread is already performing an ibwait using the same descriptor and another thread tries to calls ibwait on the same descriptor.
Solution:
Error Condition: Event Notification was cancelled due to a reset of the interface.
Possible Cause: ERST results when an event notification was cancelled due to a reset of the interface. An ibwait call pending in the driver returns ERST in the following situations:
An ibnotify callback may be invoked with ERST in the following situations:
Solutions:
Error Condition: The Interface lost power.
Possible Cause: EPWR results when an interface loses power. This often results when the system goes to and returns from a standby state.
Solutions:
This troubleshooting information is continued in GPIB Error Codes and Common Solutions (Part 1) and GPIB Error Codes and Common Solutions (Part 2).