Motorola R-2550 Programming Reference Manual page 58

"TST?
Description:
Syntax:
Query
Standard RS-232
Response Syntax:
IEEE 488.2
Response Syntax:
Parameters:
Motorola Communications Analyzer
Programming Reference
The *TST? query causes the analyzer to perform a self-test.
Description: Self-test Result
units: None
Resolution: N/A
Range: 0: self-test passed
1:
self-test failed
Self-Test Query