HP 83751A Programming Manual page 247

Bus Control Errors
201 -310, "System error;Another Controller Is On The HP-IB Bus
(201)"
Indicates that during a Flatness Calibration, the instrument was
trying to establish the control of the Power Meter, but figured out
another controller is on the HP-IB bus. Flatness Calibration is
aborted.
204 -310, "System error;Comma.nd Send Error-No HP-IB Devices
Found (204)"
Indicates that during a Flatness Calibration, the instrument was
sending a command to an HP-IB device, but could not find it.
Flatness Calibration is aborted.
205 -310, "System error;Cannot Find Power Meter On HP-IB Bus
(205)"
Indicates that during a Flatness Calibration, the instrument was
trying to establish the control of a supported Power Meter, but
could not knd it. Flatness Calibration is aborted.
206 -310, "System error;Meter Returns Error Message (206)"
Indicates that during a Flatness Calibration, the HP-R3 Power Meter
error checldng returns an error message of some type.
207 -310, "System error;Meter Data Measured Is Invalid or Out Of
Range (207)"
Indicates that during a Flatness Calibration, a reading return value
which HP-IB Power Meter measured is invalid or out of range.
Flatness Calibration is aborted.
-310, "System error;Unable To Receive Message From Meter
208
(208)"
Indicates that during a Flatness Calibration, a time out is happened
while the instrument was waiting to receive a message from the
Power Meter. Flatness Calibration is aborted.
Error Messages
4-25