Modbus-Rtu Slave Mode - Omron SYSMAC CS1W-SCB41-V1 Operation Manual

Troubleshooting

11-3-6 Modbus-RTU Slave Mode

Serial commu- Indicator
nications status
mode
Serial commu- ---
nications mode
is not set to
Modbus-RTU
slave mode.
Serial commu- The SD@/RD@
nications mode and COM@
is set to Mod- indicators do
bus-RTU slave not flash at all.
mode. (Communica-
tions have not
been electri-
cally estab-
lished.)
The RD@ and
COM@ indica-
tors are flash-
ing, but the
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.)
344
Status CIO Area
information,
etc.
--- Bits 12 to 15 (Serial
Communications
Mode) of CIO Area
words n + 5/n + 15
are set to a value
other than A Hex.
--- ---
There is no CIO Area words n +
transmission 8/n + 18 (transmis-
error. sion error status)
are set to 0000 Hex.
CIO Area words n +
5/n + 15 (port set-
tings in the System
Setup) do not corre-
spond to the set-
tings of the remote
device.
Cause
Serial communica- Set bits 08 to 11 (Serial
tions mode is not Communications Mode) of
set correctly. DM Area words m/m + 10
to A Hex (Modbus-RTU
slave mode).
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.
Commands are not Reset the serial port at the
being set from the host, and rewrite the pro-
host. gram.
This is a hardware Set bits 08 to 11 (Serial
error. Communications Mode) of
DM Area words m/m + 10
to F Hex (Loopback Test
Serial Communications
Mode). Then, connect the
connector wire for a loop-
back test and conduct a
loopback test by turning
ON bit 14 (Loopback Test
Switch) of CIO Area word
n. The test data is
reflected in CIO Area
words n+9/n+19. If an
error occurs during the
test, replace the Board or
Unit.
The System Setup Correct the setting in DM
in DM Area words m Area words m + 6/m + 16
+ 6/m + 16 of the of the Board or Unit (Mod-
Board or Unit (Mod- bus slave address) so that
bus-RTU slave they correspond to the set-
address) does not tings at the host device.
correspond to the
Correct the command
settings for the
frame (destination Mod-
remote device.
bus slave address) and the
The command for- program.
mat and data length
of the data sent
from the host are
incorrect.
Section 11-3
Remedy