3-9
Note 1. In many cases, signal cable errors will be detected together with encoder or resolver discon-
nection errors.
Note 2. If the cable contact is improper, the resistance of the cable will vary slightly. To check a slight
difference in resistance in such a case, use a multimeter that has a mΩ range.
Encoder (Resolver) Disconnection
• An alarm will go off if there is no encoder or resolver voltage output.
Alarm Indication
U Series: A. C3, A. C4
H Series: E1
M Series: A. L-6
R Series: RE. E
Probable cause Item to check Countermeasure
Abnormal encoder signal lines.
Abnormal resolver signal lines.
• The signal lines are discon-
nected.
• The signal lines are short-cir-
cuited.
* Check the resistance of the
cable alone.
• Replace the encoder cable.
• Replace the resolver cable.
Motor overheating. • The surface temperature of the
encoder exceeds 70°C. (Applica-
ble to H and R Series only.)
• Decrease the motor ambient
temperature.
• Take the same countermeasures
as those against motor overload.
Encoder or resolver malfunctions. • Do not turn any output signal of
the encoder on and off if the volt-
age of the output signal between
the output terminal and the pow-
er supply ground of the encoder
is 2.5 V min.
• The resistance between each
combination of these terminals
of the resolver is far from the
rated resistance.
SIN energized terminals:
100 Ω
COS energized terminals:
110 Ω
Resolver output terminals:
5,000 Ω
• Replace the motor.
Signal errors caused by noise. • None of the above items applies.
• The frequency and conditions of
error are indefinite.
Take countermeasures against
noise. Refer to Chapter 4
Countermeasures Against Noise.
Note 1. In many cases, signal cable errors will be detected together with encoder or resolver discon-
nection errors.
Note 2. If the cable contact is improper, the resistance of the cable will vary slightly. To check a slight
difference in resistance in such a case, use a multimeter that has a mΩ range.
Servo Driver Errors Chapter 3
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