As errors are detected, error messages are placed in a queue. This queue is first in, first out and can hold a maximum of 10 messages. If the queue overflows, the last error message in the queue is replaced with the error message:
–350, “Queue overflow”
Any time the queue overflows, the least recent error messages remain in the queue, and the most recent error message is discarded. Reading an error message from the head of the queue removes that error message from the queue, and opens a position at the tail of the queue for a new error message, if one is subsequently detected.
When all error messages have been read from the queue, further error queries shall return
0, “No error”
The error queue shall be cleared when any of the following occur (IEEE 488.2, section 11.4.3.4):
• Upon power up
• Upon receipt of a *CLS command
• Upon reading the last error message from the queue