Omron CJ1W-SCU32 Operation Manual page 301

Error conditions
Serial Indicator
communications status
mode
Serial communi- The RD@ indica-
cations mode is tors flash, but the
set to Modbus- response was not
RTU Slave Mode. returned from the
host.
The SD@ indicator
does not flash at
all. (Communica-
tions were electri-
cally established.)
Note The system settings can not be changed unless the power supply is cycled, the Unit is restarted,
or the port is restarted. Refer to 1-8 Basic Operating Procedure for details.
CJ-series Serial Communications Units Operation Manual for NJ-series CPU Unit(W494)
Confirmation of
device variable
Status
for CJ-series Unit,
information,
etc.
etc.
There is no ---
transmission
error.
There is a *_P1(orP2)_TransErr
transmission (Transmission error) is
error. set to TRUE, or any of
*_P1(orP2)_OverRun
Err (Overrun Error),
*_P1(orP2)_FramingE
rr (Framing Error),
*_P1(orP2)_ParityErr
(Parity Error),
*_P1(orP2)_FCSErr
(FCS Check Error) is
set to TRUE.
9 Troubleshooting and Maintenance
Cause
Cables are incorrectly Check the wiring.
connected.
The RS-422A/485
port setting (2-wire or
4-wire) is incorrect.
Adapters such as the
NT-AL001 are incor-
rectly wired or set.
This is a transmission Conduct a loopback test to
circuit hardware error. check the transmission lines.
If an error occurs during the
test, replace the Unit.
The destination Mod- Correct the destination Mod-
bus slave address in bus slave address in the com-
the command frame is mand frame.
set to 0, i.e., it is set
for a broadcast.
The communications Review the System Settings,
conditions and baud the host's settings and pro-
rate do not match the gram (such as commands
settings at the host. and frame format) based on
the response contents, and
the transmission error codes
in *_P1(orP2)_TransErrSta
(Transmission Error Status).
There is noise interfer- Use shielded twisted-pair
ence. cables.
Lay power lines separately by
using ducts.
Review the installation envi-
ronment to reduce noise inter-
ference.
There is an error in Append the correct CRC
the CRC code code.
appended to the host
command frame.
Remedy
9
9-23