64
3 Remote Operation
3.6.4 Motor Errors
51
: Chopper head memory fail. On each motor startup, the SR542
attempts to read calibration and identification information from
the chopper head. Error 51 indicates that this read operation has
failed. Motor startup cannot proceed. Please contact SRS to ar‑
range for the return of the chopper head for service.
52
: Chopper head disconnected. The chopper head has become dis‑
connected from the control unit. Please check the chopper head
cable.
3.6.5
Device-Dependent Errors
71
: Maximum frequency. The chopper configuration has resulted in
an internal clock frequency that exceeds the maximum (23.1 kHz).
The Source Clock and Shaft Reference Clock cannot exceed 23.1 kHz.
The user should adjust the Source frequency, modify the
Multiplier
(reduce
n
or increase
m
), or change the
Control
track to a track with
higher slot count.
72
: No inner slots detected. This can occur if the installed blade has no
apertures for the inner track. If using a single‑frequency chopper
blade, change the
Control
track to Outer or Shaft. Otherwise, check
to make sure the opto‑interrupter for the inner track, positioned on
the outer‑most diameter of the chopper blade, is not blocked.
73
: No outer slots detected. Check to make sure the opto‑interrupter
for the outer track, which is positioned slightly higher, is not
blocked.
74
: Motor lost. If this error occurs during startup, it indicates that the
shaft encoder index was not found. Check to make sure the chop‑
per blade can freely rotate. If this error consistently occurs dur‑
ing steady motor operation, ensure the chopper head cable shield
is properly grounded (see Section 5.1). If the issue persists, it is
possible that the shaft encoder or chopper head cable have been
compromised. Return the chopper head and cable for service.
3.6.6
Other Errors
254
: Too many errors. The error buffer is full and no longer able to store
additional errors. Either read out the errors with repeated
LERR?
queries, or clear the error queue with a
*CLS
command. The error
buffer can also be cleared from the front panel (see discussion of
SR542 Precision Optical Chopper
