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7-3SectionMaintenance of the NT31/NT31C
241
Error Details RemedyDisplayed Probable Cause
Time-out Error The connecting cables are not
connected correctly. (Send/Receive)
Check the communication cable connection and
perform a conductivity test. If there is a fault,
replace the cable. For details on communication
cables, refer to Section 4 Connecting to the Host
from the RS-232C Port, and Section 5 Connecting
to the Host from the RS-422A/485 Port.
The communication service of the
host is stopped. (Send/Receive)
Check that the host is capable of communicating
with the NT31/NT31C (confirm that the
communication settings of the host and
NT31/NT31C match).
Time-out Interval is too short. (Send) Set a longer value for Time-out Interval at the host
side.
Time-out Interval is too short.
(Receive)
Set a longer value for Time-out Interval in the
System Menu. (6-9-12 Setting the Time-out Interval,
page 185) It may also be possible to solve the
problem by shortening the host cycle time.
PC Unit No. Error The unit # does not match that set
on the PC.
Re-set the unit number at the host side to 0.
Noise caused data corruption during
communication.
Carry out grounding work in accordance with the
conditions by referring to 3-1-4 Grounding, page 34.
NAK received —— Check the settings for allocated words and bits.
If noise is a possible factor, distance the cable from
sources of noise and insert a noise filter in the
power supply line.
If using the equipment in a location subject to a lot
of noise, use a cable with a high degree of
protection against noise for the transmission route.
Also make the cable as short as possible.
Undefined Command
E
The host is not supported. Check the PC model used for the host.
Error
Instruction level 3 is not effective. Check that the instruction level setting for the host is
level 1, 2, 3.
Data Over Flow Error Communication command from the
host is too long. (With memory link)
Set flow control method in the host.
Increase transmission interval.
Command transmission to the host
is not possible.
Check the communication cable.
Check the control method at the PT and the host.
Increase the communication on speed when it to
slow.
7-3 Maintenance of the NT31/NT31C
Carry out maintenance work in order to ensure that the NT31/NT31C is always
used in its optimum condition.
WARNING
Do not attempt to take the unit apart and do not touch any inter-
nal parts while the power is being supplied. Doing either of
these may result in electrical shock.
It is advisable to have a spare NT31/NT31C available to minimize system down-
time in the event of an NT31/NT31C failure or if the screen display becomes diffi-
cult to read due to deterioration of the display unit.
When the backlight in the display is getting dim and the screen cannot be read
easily, replace the backlight. The backlight can be replaced at the rear of the
NT31/NT31C while it is mounted in an operation panel.
Spare PT
Backlight