YASKAWA S-V Series User Manual page 198

9 Troubleshooting
Problem
Linear Scale
Position
Difference Error
(The position
saved in the host
controller when
the power was
turned OFF is
different from the
position when the
power is next
turned ON.)
Overtravel (OT)
9-28
Probable Cause
Noise interference due to improper
linear scale connection cable speci-
fications
Noise interference due to length of
linear scale connection cables
Noise interference due to damaged
linear scale connection cables
Excessive noise interference at the
linear scale connection cables
FG potential varies because of
influence of machines such as weld-
ers at the servomotor.
SERVOPACK pulse counting error
due to noise interference
Excessive vibration and shock to
the serial converter unit
A serial converter unit fault
occurred.
A linear scale fault occurred.
A SERVOPACK fault occurred.
Host controller serial data reading
error
Forward or reverse run prohibited
signal is input.
Forward or reverse run prohibited
signal is malfunctioning.
Investigative Actions
The specifications of linear scale
connection cables must be:
Shielded twisted-pair or shielded
multi-core twisted-pair wire with
2
core 0.12 mm min. and tinned
annealed copper twisted wire.
Check the length of linear scale
connection cables.
Check if any of the linear scale con-
nection cables is bent or if its
sheaths are damaged.
Check if any of the linear scale con-
nection cables is bundled with a
high-current line or near high-cur-
rent line.
Check if the machines are correctly
grounded.
Check if there is noise interference
on the input/output signal line from
the serial converter unit.
Check if vibration from the machine
occurred or the serial converter unit
installation is incorrect (mounting
surface accuracy and fixing).
–
–
–
Check the error detection section at
the host controller.
Check if the host controller is exe-
cuting data parity checks.
Check for noise in the input/output
signal line between the SERVO-
PACK and the host controller.
Check if the voltage of input signal
external power supply (+24 V) is
correct.
Check if the overtravel limit switch
operates properly.
Check if the overtravel limit switch
is connected correctly.
Check the settings for PnB0F and
PnB10.
Check the fluctuation of the input
signal external power supply (+24
V) voltage.
Check if the overtravel limit switch
operates correctly.
Check if the overtravel limit switch
wiring is correct. (check for dam-
aged cables or loosen screws.)
(cont'd)
Corrective Actions
Use the specified linear scale con-
nection cables.
The maximum length of linear scale
connection cables:
20 m for the cable for connecting a
serial converter unit
15 m for the cable for connecting a
linear scale/hall sensor
Replace the linear scale connection
cables and correct their layout.
Correct the linear scale connection
cable layout so that no surge from
high-current lines is applied.
Ground machines correctly, and
prevent diversion to the FG at the
linear scale side.
Take measures against noise in the
serial converter unit wiring.
Reduce vibration from the machine,
or secure the serial converter unit
installation.
Replace the serial converter unit.
Replace the linear scale.
Replace the SERVOPACK.
Correct the error detection section
of the host controller.
Execute a serial data parity check.
Take measures against noise, and
again execute a serial data parity
check.
Correct external power supply (+24
V) voltage.
Correct the overtravel limit switch.
Correct the overtravel limit switch
wiring.
Set the parameters correctly.
Stabilize the external power supply
(+24 V) voltage.
Stabilize the operation of the over-
travel limit switch.
Correct the overtravel limit switch
wiring.