Omron SYSMAC CS1W-SCB41-V1 Operation Manual page 374

Troubleshooting
Serial commu- Indicator
nications status
mode
Serial commu- The RD@ and
nications mode COM@ indica-
is set to Mod- tors are flash-
bus-RTU slave ing, but the
mode. response has
not been
returned from
the host.
For the Unit, the
SD@ indicator
does not flash
at all (Commu-
nications have
been electri-
cally estab-
lished.)
Status CIO Area
information,
etc.
There is no ---
transmission
error.
---
There is a In CIO Area words n
transmission + 8/n + 18, bit 15
error. (transmission error
status) is turned
ON, and bit 07(CRC
error), bit 04 (over-
run error), bit 03
(framing error), or
bit 02 (parity error)
is turned ON.
Cause
Cables are incor- Check the wiring.
rectly connected.
The RS-422A/485 Reset the port to the cor-
port setting (2-wire rect wiring setting.
or 4-wire) is incor-
Wire all nodes using the 4-
rect.
wire method.
Adapters such as
the NT-AL001-E are
incorrectly wired or
set.
This is a transmis- Conduct a loopback test in
sion circuit hard- serial communications
ware error. mode to check the trans-
mission lines. If an error
occurs during the test,
replace the Board or Unit.
The destination Correct the destination
Modbus slave Modbus slave address in
address in the com- the command frame.
mand frame is set to
0, i.e., it is set for a
broadcast.
The communica- Review the System Setup,
tions conditions and the host's settings and pro-
baud rate do not gram (such as commands
match the settings and frame format) based
at the host. on the response contents,
and the transmission error
codes in CIO Area words n
+ 8/n + 18.
There is noise inter- Use shielded twisted-pair
ference. cables.
Lay power lines sepa-
rately using ducts.
Review the installation
environment to reduce
noise interference.
There is an error in Append the correct CRC
the CRC code code.
appended to the
host command
frame.
Section 11-3
Remedy
345