Maintenance Of The Nt21 - Omron NT21 - SETUP MANUAL 10-2001 Setup Manual

Maintenance of the NT21

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

Maintenance of the NT21

Backing Up Screen Data
Preparing a Spare PT
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.
Command 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 NT21 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.
Always back up the screen data and store it in a safe place in case a problem
develops and the NT21 needs to be replaced or repaired.
It is advisable to have a spare NT21 available to minimize system downtime in
the event of an NT21 failure or if the screen display becomes difficult to read due
to deterioration of the display unit.
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 NT21 (confirm that the communication
settings of the host and NT21 match, and
connection between the host and NT21 if flow
control is set).
Set a longer value for Time-out Interval at the host
side.
Set a longer value for Time-out Interval in the
System Menu. (6-9-10 Setting the Time-out Interval,
page 142) 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 18.
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 command 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 baud rate if it is too slow.
WARNING
Section 7-3
183