HP 8901B Operation And Calibration Manual page 339

Model 8901B
Operation
Error Message
Code
40-89
Service-related errors.
Error 24
Error 24 always causes the issuance of a Require Service message on the
HP-IB.
Corrective Action
Refer to service section of HP 8901B instrument manual.
Errors 40 through 89
Service errors are normally disabled.
Error Message Summary
3-251