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Troubleshooting Section 7-1
The graph display does not
change.
One of the percentage display set-
tings — −100%, 0%, or 100% — is
incorrect.
Set the −100%, 0%, and 100% values in the following
relationship:
−100% value < 0% value < 100% value
The trend graph display
does not agree with the
actual time axis.
The cycle for graph display update
processing is longer than the set
sampling cycle.
Delete other elements on the same screen as the
trend graph that are allocated to the host and have a
high update frequency. Or lengthen the sampling
cycle.
The Programming Console
function cannot be used.
The communications settings are
incorrect.
Set the communications method as follows when
using the Programming Console function.
• With C-series PLC: 1:1 NT Link
• With CS/CJ-series PLC:
1:N NT Link (standard or high-speed)
A Programming Console is con-
nected.
It is not possible to use a Programming Console and
the Programming Console function at the same time.
Disconnect the Programming Console.
The PLC does not support the Pro-
gramming Console function.
Not all PLCs support the Programming Console func-
tion. Check the model of PLC you are using. (6-12
Programming Console Function)
The system program for other ven-
dor’s PLCs has been installed. (PLC
models other than OMRON.)
The Programming Console function can be used only
when the system program for OMRON PLCs is
installed. Install the correct system program.
The Device Monitor func-
tion cannot be used.
The communications settings are not
correct.
Set the communications method as follows when
using the Device Monitor function.
• With C-series PLCs: 1:1 NT Link or 1:N NT Link
• With CS/CJ-series PLCs:
1:N NT Link (standard or high-speed)
The PLC does not support the Device
Monitor function.
Not all PLCs support the Device Monitor function.
Check the model of PLC you are using. Refer to 6-13
Device Monitor Function for details.
The system program installed in the
PT is for a PLC maker other than
OMRON.
The Device Monitor function can be used only when
the PT is connected to a PT with the system program
for OMRON PLCs installed. Install a system program
that supports the Device Monitor function.
The memory table display
contents differ from the ini-
tial value set at the Sup-
port Tool.
Since the memory table is allocated
to the host memory, the display is
updated in accordance with the con-
tents of the host memory.
When the contents of the memory table are set as a
fixed value, do not allocate the memory table to the
host.
The battery voltage has dropped and
the data in the memory table has
been destroyed.
Replace the battery and execute memory table initial-
ization. (7-3-1 Replacing the Battery, page 241, and
6-4-5 Initializing the Memory Tables, page 141)
Since ON is set for the resume func-
tion, the initial values of the screen
data memory are not written to the
memory tables.
Execute memory table initialization. (6-4-5 Initializing
the Memory Tables, page 141)
If the resume function does not need to be used, use
the NT631/NT631C with the resume function OFF.
(6-9-10 Setting the Resume Function, page 177)
The numeral memory table is speci-
fied as the destination for a mathe-
matical table’s results.
Calculations are executed continuously while the PT
is operating and the calculation results are automati-
cally written to the memory table. Specify another
numeral memory table or a word in the host.
NT631/NT631C
Symptoms
Cause Remedy