The SCPI specifications define a standard error reporting scheme --- Error/Event Queue. This is a FIFO (First In First Out) queue, which records errors and events. The maximum number of errors/events that can be recorded in the PLZ-4W/PLZ-4WL/PLZ-4WH is 255. Each error/event can be read by the SYSTem:ERRor query.
The response to this query contains a numerical part (error/event number) and a textual description, such as:
-222,"Data out of range"
The error/event queue is empty when the *CLS common command is sent, when the last item in the queue is read, or when the PLZ-4W/PLZ-4WL/PLZ-4WH is turned on. When the error/event queue is empty, the query returns the following: