341
Troubleshooting Section 11-3
Serial com-
munica-
tions mode
is set to
protocol
macro.
The SD@/
RD@ and
COM@ indi-
cators are
flashing, but
the Unit or
Board can-
not perform
communi-
cations or a
communi-
cations
error some-
times
occurs.
A transmission
error some-
times occurs.
Bit 15 (Transmission
Error) of the words
allocated in the CIO
Area n+8/n+18 is set
to ON.
There is an error in
bits 0 to 14.
The wiring is faulty.
The RS-422A/485 port
terminating resistance
setting is incorrect.
Adapters such as the NT-
AL001-E are incorrectly
wired, or the terminating
resistance setting is
incorrect.
Check the wiring.
Turn ON the terminating
resistance of the Board
and the last node by
using the terminating
resistance switch. Turn
OFF the terminating
resistance of other
nodes.
A communications error
frequently occurs due to
noise and so on.
Use shielded twisted pair
cables.
House the communica-
tions cables in a different
duct from those for power
lines and so on.
Review the operating
environment to prevent
noise problems.
Programming retry pro-
cessing for communica-
tions if necessary.
The RDY
and ERC
indicators
are flash-
ing (ERR/
ALM).
--- Bit 00 (Protocol Data
Error) of the words
allocated in the CIO
Area n+1 is set to
ON.
The protocol macro data
SUM value is abnormal.
Use CX-Protocol to trans-
fer the correct protocol
data.
The RDY
indicator is
lit and the
ERC indica-
tor is flash-
ing (ERR/
ALM).
--- Bits 00 to 03 (Port
Status Error Code)
of the words allo-
cated in the CIO
Area n+9/n+19 are
set to a value other
than 0 Hex. (An error
has occurred.)
An error has been
detected in the protocol
macros, making the oper-
ation impossible.
See note on page 343.
Serial
communi-
cations
mode
Indicator
display
Status
information,
etc.
Words allocated in
the CIO Area
Cause Remedy
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