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7-1
Section
Troubleshooting
174
7-1
Troubleshooting
When a fault relating to the operation of the NT21 occurs, find the symptoms in
the table below and respond by following the corresponding Remedy indicated
in the table.
Note
1. Confirm system safety before turning the power ON/OFF.
2. Do not disassemble the PT for repair or modification.
Otherwise the product may malfunction.
NT21 Symptoms
Cause
Remedy
Nothing is displayed on
the screen.
Power is not being supplied.
Check the connections and make sure that power is
supplied correctly. (3-1-3 Power Supply Connection,
page 17)
Power supply fuse has blown.
Contact your OMRON service center.
Screen No. 0 has been read at the
host side.
This is not an error. Change the screen number
from screen number 0. (Setting the screen number
to 0 turns the screen off.)
The system startup waiting time has
not elapsed yet.
This is not an error. The display will appear after the
waiting time has elapsed.
Cannot communicate with
the NT Support Tool
The Transmit mode has not been
established.
Display the System Menu and select the Transmit
mode. (6-6 Transmitting the Screen Data, page 123)
t e
Suppo t oo
Not connected to the NT Support
Tool.
Check the installation of the connector cable. (3-3
Connecting to the NT Support Tool, page 28)
The PT model setting and direct
connection setting at the NT Support
Tool do not match the NT21.
Using the PT Configuration settings of the NT
Support Tool, set the PT model and direct
connection settings that match the NT21.
Cannot communicate with
the host
Cannot switch from the
system initializing screen.
Communication error
Memory switch settings do not
match.
Check the communication setting in the Memory
Switch menu of the Maintenance mode, and match
the communication protocol settings for the host and
NT21. (6-7 Setting Conditions for Communications
with Host by Using Memory Switches, page 125)
Communication error
message is displayed
when communicating to
the host.
NT21 and host are not correctly
connected.
Check that the type, length, and installation of the
connector cable match the specifications. (Section 4
Connecting to the Host from the RS-232C Port, and
Section 5 Connecting to the Host from the
RS-422A/485 Port)
An RS-422A/485 connection is being
used and the terminator setting is
incorrect.
Make the Link Adapter and PC terminating
resistance settings correctly. (Section 5 Connecting
to the Host from the RS-422A/485 Port)
In an NT Link (1:N) connection, there
is duplication in the unit numbers.
Make the settings again so that there is no
duplication. (6-7-4 Setting the NT Link (1:N) Method
(Standard/High-speed), page 129)
The power to the NT21, NT-AL001
or host is OFF.
Check the power supply.
The buzzer has sounded
and the RUN Indicator is
O
Malfunction due to external noise
Carry out grounding work in accordance with the
conditions by referring to 3-1-4 Grounding, page 18.
a d t e
U
d cato s
OFF.
The NT21 has developed trouble.
Contact your OMRON service center.
The touch panel does not
respond.
Malfunction due to external noise
Carry out grounding work in accordance with the
conditions by referring to 3-1-4 Grounding, page 18.
espo d
The touch panel is broken.
Test the touch panel with I/O Check in the
MAINTENANCE MODE menu. If there is an error,
contact your OMRON service center.
The PC mode has
changed to the monitor
mode.
The NT21 changes the mode when
host link communication is used.
This is an NT21 specification. When using a PC that
can also be connected using the NT Link method,
use an NT Link connection (there is no mode to
change with the NT Link method).
The graph display does
not update.
One of the percentage display
settings — –100%, 0%, or 100% —
is incorrect.
Set the –100%, 0%, and 100% values in the
following relationship:
–100% value < 0% value < 100% value