YASKAWA LonWorks SI-W3 Installation Manual page 56

9 Troubleshooting
If communication stops while the drive is running, use these questions as a guide to help
remove the fault:
• Is the option properly installed?
• Is the communication line properly connected to the option? Is it loose?
• Did a momentary power loss interrupt communications?
Code Name
Option
bUS
Communication Error
Option Card External
EF0
Fault
56
Causes
The drive did not receive a
signal from the controller.
The communications cable
wiring is incorrect.
An existing short circuit or
communications disconnection
A data error occurred due to
electric interference
Option is damaged
Connection Time-out
The option received an external
fault from the controller.
A programming error occurred
on the controller side.
YASKAWA TOEP C730600 93B LonWorks Installation Manual
Possible Solutions
• Check for wiring errors.
• Correct the wiring.
Check disconnected cables and short
circuits and repair as needed
• Prevent noise in the control circuit,
main circuit, and ground wiring.
• If you identify a magnetic contactor
as a source of noise, install a surge
absorber to the contactor coil.
• Use only recommended cables or
other shielded line. Ground the shield
on the controller side or the drive
input power side.
• Separate all communication wiring
from drive power lines. Install an
EMC noise filter to the drive power
supply input.
• Counteract noise in the master
controller (PLC).
If there are no problems with the wiring
and the error continues to occur, replace
the option.
The option Receive Heartbeat timer
timed out.
• Make sure that Receive Heartbeat
time is set properly.
• Check the option connection and
communication signal.
1. Find the device that caused the
external fault and remove the caus.
2. Clear the external fault input from
the controller.
Examine the operation of the controller
program.