YASKAWA SGD7S-****20A Series Product Manual page 485

12.5 Troubleshooting Based on the Operation and Conditions of the Servomotor
Problem
Absolute
Encoder
Position
Deviation
Error (The
position
that was
saved in the
host con-
troller when
the power
was turned
OFF is dif-
ferent from
the posi-
tion when
the power
was next
turned ON.)
Overtravel
Occurred
12-66
Possible Cause
A failure occurred in the
encoder.
A failure occurred in the
SERVOPACK.
Host Controller Multiturn
Data or Absolute Encoder
Position Data Reading Error
The P-OT/N-OT (Forward
Drive Prohibit or Reverse
Drive Prohibit) signal was
input.
The P-OT/N-OT (Forward
Drive Prohibit or Reverse
Drive Prohibit) signal mal-
functioned.
There is a mistake in the allo-
cation of the P-OT or N-OT
(Forward Drive Prohibit or
Reverse Drive Prohibit) sig-
nal in Pn50A = n.X or
Pn50B = n.X.
Confirmation
–
–
Check the error detec-
tion section of the host
controller.
Check to see if the host
controller is executing
data parity checks.
Check for noise interfer-
ence in the cable
between the SERVO-
PACK and the host con-
troller.
Check the external power
supply (+24 V) voltage for
the input signals.
Check the operating con-
dition of the overtravel
limit switches.
Check the wiring of the
overtravel limit switches.
Check the settings of the
overtravel input signal
allocations (Pn50A/
Pn50B).
Check for fluctuation in
the external power supply
(+24 V) voltage for the
input signals.
Check to see if the opera-
tion of the overtravel limit
switches is unstable.
Check the wiring of the
overtravel limit switches
(e.g., check for cable
damage and loose
screws).
Check to see if the P-OT
signal is allocated in
Pn50A = n.X.
Check to see if the N-OT
signal is allocated in
Pn50B = n.X.
Continued from previous page.
Correction Reference
Turn OFF the power
supply to the servo
system.
–
Replace the Servomo-
tor or linear encoder.
Turn OFF the power
supply to the servo
system.
–
Replace the SERVO-
PACK.
Correct the error detec-
tion section of the host
–
controller.
Perform parity checks
for the multiturn data or
–
absolute encoder posi-
tion data.
Implement counter-
measures against noise
and then perform parity
checks again for the
–
multiturn data or abso-
lute encoder position
data.
Correct the external
power supply (+24 V)
–
voltage for the input
signals.
Make sure that the
overtravel limit switches –
operate correctly.
Correct the wiring of
the overtravel limit
page 5-28
switches.
Set the parameters to
page 5-28
correct values.
Eliminate fluctuation
from the external power
–
supply (+24 V) voltage
for the input signals.
Stabilize the operating
condition of the over-
–
travel limit switches.
Correct the wiring of
the overtravel limit
–
switches.
If another signal is allo-
cated in Pn50A
=n.X, allocate the
P-OT signal instead.
page 5-28
If another signal is allo-
cated in Pn50B
=n.X, allocate the
N-OT signal instead.
Continued on next page.