Agilent Technologies N1911A Programming Manual page 647

Example
Error Messages
• If P- Series power sensor is not present, the error –241, "Hardware
N1911A/1912A P-Series Power Meters Programming Guide
TRAC1:MEAS:INST:REF? 25
Missing" occurs.
This command return the time instant
for trace 1 when the power transitioned
through 25 % reference level.
TRACe Subsystem 13
619