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9-3SectionBoard Replacement
130
Serial commu-
nications
mode
RemedyCauseI/O memoryStatus
information,
etc.
Indicator
display
Serial commu-
nications mode
is set to NT
Link.
The COMMj
indicators are
flashing, but a
communica-
tions error
sometimes oc-
curs in the PT.
--- ---
Cables are incor-
rectly connected.
The RS-422A/485
port setting (2-wire
or 4-wire) is incor-
rect.
Adapters such as
the NT-AL001-E are
incorrectly wired or
set.
Review the wiring or
switch settings.
Check whether the termi-
nating resistances of the
host computer and the last
node are set to ON, and
the terminating resistances
of other nodes are set to
OFF.
A communications
error frequently oc-
curs due to noise,
etc.
Review the wiring and
installation environment.
Increase the number of re-
tries for the PT as re-
quired.
The communica-
tions monitoring
time for the PT is in-
sufficient.
Increase the communica-
tions monitoring time for
the PT.
The load on the PC
is too high.
Lighten the load on the
PC.
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.
Note The PT serial port must be set for a 1:N NT Link. The PT will not be able to com-
municate with a Serial Communications Board if the PT is set for a 1:1 NT Link.
9-3 Cleaning and Inspection
Use the cleaning and inspection methods described here for daily maintenance
of the devices.
9-3-1 Cleaning
To keep the Serial Communications Board in optimum condition, regularly clean
the Serial Communications Board as follows:
• Wipe the surface of the Serial Communications Board daily with a soft, dry
cloth.
• If any dirt cannot be removed with a dry cloth, moisten the cloth with a mild de-
tergent diluted to 2%, and squeeze out any excess moisture before wiping the
Serial Communications Board.
• Do not adhere materials, such as gum, vinyl, or tape to the Serial Communica-
tions Board for long periods of time. Doing so may cause stains on the device.
Remove any adhered materials when cleaning the Serial Communications
Board.
Note Never use benzene, paint thinner, or other volatile solvents, and do not use
chemically treated cloths.