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Maintenance Section 8-3
8-2-5 RS-232C Unit Troubleshooting
8-3 Maintenance
This section describes the routine cleaning and inspection recommended as
regular maintenance.
8-3-1 Cleaning
Clean the DeviceNet Units regularly as described below in order to keep it in
its optimal operating condition.
• Wipe the Unit with a dry, soft cloth for regular cleaning.
• When a spot cannot be removed with a dry cloth, dampen the cloth with a
neutral cleanser, wring out the cloth, and wipe the Unit.
• A smudge may remain on the Unit from gum, vinyl, or tape that was left
on for a long time. Remove the smudge when cleaning.
!Caution Never use volatile solvents such as paint thinner or benzene or chemical
wipes. These substances could damage the surface of the Unit.
8-3-2 Inspection
Be sure to inspect the system periodically to keep it in its optimal operating
condition. In general, inspect the system once every 6 to 12 months, but
inspect more frequently if the system is used with high temperature or humid-
ity or under dirty/dusty conditions.
Symptom Probable cause Possible remedy
The RS-232C Unit’s ERR indicator is lit. The RS-232C Unit is damaged. Replace the RS-232C Unit.
RS-232C port communications error
(the Unit’s RD and SD indicators are
not lit).
The wiring is incorrect, or the cables
are not connected properly.
Check the wiring with the RS-232C
Unit and correct it if necessary.
The RS-232C port’s parameters do not
match those of the RS-232C Unit.
Reset the RS-232C port’s parameters
to match the parameters of the RS-
232C Unit.
Parameter Error Flag (bit 01 or 09) in
communications status word is ON.
The parameters are set incorrectly. Reset the parameters correctly using
the PARAMETER SET command, then
execute the RS-232C PORT RESET
command or restart the RS-232C Unit.
Parity Error Flag (bit 04 or 12) in com-
munications status word is ON.
The parity setting does not match the
setting in the RS-232C Unit.
Reset the RS-232C port’s parity setting
to match the parity of the RS-232C
Unit.
Overrun Error Flag (bit 05 or 13) in
communications status word is ON.
The baud rate does not match the set-
ting in the RS-232C Unit.
Reset the RS-232C port’s baud rate to
match the baud rate of the RS-232C
Unit.
Framing Error Flag (bit 06 or 14) in
communications status word is ON.
The character block settings (data
length, parity, and stop bits) do not
match those in the RS-232C Unit.
Reset the RS-232C port’s character
block (data length, parity, and stop bits)
to match the character block of the RS-
232C Unit.
Receive Buffer Error Flag (bit 07 or 15)
in communications status word is ON.
The receive buffer has overflowed. The receive buffer for each of the RS-
232C Unit’s ports is 1,024 bytes.
Increase the reading frequency so that
the receive buffer does not overflow.
If the receive buffer has overflown, exe-
cute the RS-232C PORT RESET com-
mand or restart the RS-232C Unit.
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