Omron SYSMAC CS1W-SCB41-V1 Operation Manual page 365

Troubleshooting
Serial commu- Indicator
nications mode display
Serial communi- The SD@/RD@
cations mode is and COM@ indi-
set to NT Link. cators are flash-
ing, but a
communica-
tions error
sometimes
occurs in the PT.
Note
336
Status Words allo-
information, cated in the
etc. CIO Area
--- ---
1. The PT serial port must be set for a 1:N NT Link. The PT will not be able
to communicate with a Serial Communications Board or Unit if the PT is
set for a 1:1 NT Link.
2. The System Setup cannot be changed unless the power supply is cycled,
the Board or Unit is restarted, the port is restarted, or the STUP(237) in-
struction is executed. Refer to 1-7 Comparison to Previous Products for de-
tails.
Cause
Cables are incor- Review the wiring or switch
rectly connected. settings.
The RS-422A/485 Check whether the termi-
port setting (2-wire nating resistances of the
or 4-wire) is incor- host computer and the last
rect. Unit are set to ON, and the
terminating resistances of
Adapters such as the
other Units are set to OFF.
NT-AL001-E are
incorrectly wired or
set.
A communications Review the wiring and
error frequently installation environment.
occurs due to noise,
Increase the number of
etc.
retries for the PT as
required.
The communica- Increase the communica-
tions monitoring time tions monitoring time for the
for the PT is insuffi- PT.
cient.
The load on the PLC Lighten the load on the
is too high. PLC.
Reduce the number of PTs
connected to each serial
port by using other ports for
some of the PTs.
Adjust the timeout and retry
settings in the PT.
Section 11-3
Remedy