Omron EJ1 User Manual page 187

Determining Errors from Indicators
HFU
Status
ERR Red, flashing
166
Possible causes
The power supply to the PLC
was interrupted after communi-
cations were established
between the PLC and EJ1.
The communications cable was
broken after communications
were established between the
PLC and EJ1.
Parameters for a Unit that does
not exist were registered in the
Programless Upload Settings or
Programless Download Settings
of the HFU.
An error has occurred in pro-
gramless communications.
Countermeasure
Supply power to the PLC.
If the Operation Command Response Bits in the
Programless Upload Area set in PLC memory
are EEEE, write FFFF to the Operation Com-
mand Request Bits to restart communications.
Connect the cable.
If the Operation Command Response Bits in the
Programless Upload Area set in PLC memory
are EEEE, write FFFF to the Operation Com-
mand Request Bits to restart communications.
Register parameters in the Programless Upload
Settings or Programless Download Settings of
the HFU only for Units that are connected.
Check the following and correct any problems,
and then restart operation.
• Check the communications line lengths (trunk
and branch).
• Check the communications line for shorts,
breaks, or looseness.
• Check that terminating resistance is set only
on the ends on the trunk line.
• Check for excessive noise.
Section 7-2