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Chapter 18 657
Troubleshooting
Error Messages
Error Message Types
Events do not generate more than one type of error. For example, an event that generates a query error will
not generate a device-specific, execution, or command error.
Query Errors (–499 to –400) indicate that the instrument’s output queue control has detected a problem
with the message exchange protocol described in IEEE 488.2, Chapter 6. Errors in this class set the query
error bit (bit 2) in the event status register (IEEE 488.2, section 11.5.1). These errors correspond to message
exchange protocol errors described in IEEE 488.2, 6.5. In this case:
• Either an attempt is being made to read data from the output queue when no output is either present or
pending, or
• data in the output queue has been lost.
Device Specific Errors (–399 to –300, 201 to 703, and 800 to 810) indicate that a device operation did not
properly complete, possibly due to an abnormal hardware or firmware condition. These codes are also used
for self-test response errors. Errors in this class set the device-specific error bit (bit 3) in the event status
register (IEEE 488.2, section 11.5.1).
The <error_message> string for a positive error is not defined by SCPI. A positive error indicates that the
instrument detected an error within the GPIB system, within the instrument’s firmware or hardware, during
the transfer of block data, or during calibration.
Execution Errors (–299 to –200) indicate that an error has been detected by the instrument’s execution
control block. Errors in this class set the execution error bit (bit 4) in the event status register (IEEE 488.2,
section 11.5.1). In this case:
• Either a <PROGRAM DATA> element following a header was evaluated by the device as outside of its
legal input range or is otherwise inconsistent with the device’s capabilities, or
• a valid program message could not be properly executed due to some device condition.
Execution errors are reported after rounding and expression evaluation operations are completed. Rounding
a numeric data element, for example, is not reported as an execution error.
Command Errors (–199 to –100) indicate that the instrument’s parser detected an IEEE 488.2 syntax error.
Errors in this class set the command error bit (bit 5) in the event status register (IEEE 488.2, section 11.5.1).
In this case:
• Either an IEEE 488.2 syntax error has been detected by the parser (a control-to-device message was
received that is in violation of the IEEE 488.2 standard. Possible violations include a data element that
violates device listening formats or whose type is unacceptable to the device.), or
• an unrecognized header was received. These include incorrect device-specific headers and incorrect or
unimplemented IEEE 488.2 common commands.