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9-2SectionBoard Replacement
122
Serial com-
munications
mode
RemedyCauseI/O memoryStatus
information,
etc.
Indicator
status
Serial commu-
nications mode
is not set to
Host Link.
--- --- Bits 12 to 15 (Serial
Communications
Mode) of
DM 6555/DM 6550
are set to a value
other than 0 Hex.
Serial communica-
tions mode is not
set correctly.
Set bits 12 to 15 of
DM 6555/DM 6550 to
0 Hex. (Host Link).
Serial commu-
nications mode
is set to Host
Link.
The COMMj
indicators do
not flash at all.
(Communica-
tions have not
been electrical-
ly established.)
--- ---
Cables are incor-
rectly connected.
The RS-422A/485
port setting (2-wire
or 4-wire) is incor-
rect (WIRE).
Adapters such as
the NT-AL001-E
are incorrectly
wired or set.
Check the wiring.
Reset the port to the cor-
rect wiring setting.
Wire all nodes using the
4-wire method.
Commands are not
being set from the
host.
Reset the serial commu-
nications port at the host,
and rewrite the program.
There is a hard-
ware error.
Replace the Serial Com-
munications Board.
The COMMj
indicators are
flashing, but
the response
has not been
returned to the
host. (Commu-
nications have
been electrical-
ly established.)
There is no
transmission
error.
IR 20100 to
IR 20103 or
IR 20108 to
IR 20177 are
0 Hex.
The PC Setup set-
tings for the Host
Link unit No., Host
Link transmission
delay, or other set-
tings do not match
the settings for the
remote device.
The command for-
mat and data
length of the data
sent from the host
are incorrect.
Reset the settings in the
PC Setup for the Host
Link unit No., Host Link
transmission delay and
other settings so that they
match the settings at the
host device.
Correct the command
frame (header, Host Link
Unit No., terminator, etc.)
and the program.
--- Cables are incor-
rectly connected.
The RS-422A/485
port setting (2-wire
or 4-wire) is incor-
rect (WIRE).
Adapters such as
the NT-AL001-E
are incorrectly
wired or set.
Check the wiring and
switch settings, and cor-
rect if necessary.
---
This is a transmis-
sion circuit hard-
ware error.
Conduct a loopback test
in serial communications
mode to check the trans-
mission lines. If an error
occurs during the test, re-
place the Serial Commu-
nications Board.
The send delay
time setting is too
long.
Reset the parameters in
the PC Setup correctly.