Maintenance Of The Nt31/Nt31C - Omron Programmable Terminals NT31 NT31C Setup Manual

Maintenance of the NT31/NT31C

Error Details
Time-out Error
PC Unit No. Error
NAK received
Undefined Command
Error E
Data Over Flow Error
7-3

Maintenance of the NT31/NT31C

Spare PT
Backlight
Displayed Probable Cause
The connecting cables are not
connected correctly. (Send/Receive)
The communication service of the
host is stopped. (Send/Receive)
Time-out Interval is too short. (Send)
Time-out Interval is too short.
(Receive)
The unit # does not match that set
on the PC.
Noise caused data corruption during
communication.
——
The host is not supported.
Instruction level 3 is not effective.
Communication command from the
host is too long. (With memory link)
Command transmission to the host
is not possible.
Carry out maintenance work in order to ensure that the NT31/NT31C is always
used in its optimum condition.
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.
Remedy
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.
Check that the host is capable of communicating
with the NT31/NT31C (confirm that the
communication settings of the host and
NT31/NT31C match).
Set a longer value for Time-out Interval at the host
side.
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.
Re-set the unit number at the host side to 0.
Carry out grounding work in accordance with the
conditions by referring to 3-1-4 Grounding, page 34.
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.
Check the PC model used for the host.
Check that the instruction level setting for the host is
level 1, 2, 3.
Set flow control method in the host.
Increase transmission interval.
Check the communication cable.
Check the control method at the PT and the host.
Increase the communication on speed when it to
slow.
WARNING
Section 7-3
241