Troubleshooting - Mitsubishi Electric Melsec QJ71LP21 Reference Manual

8

TROUBLESHOOTING

8 TROUBLESHOOTING
In order to improve the reliability of the system, it is important to fix errors immediately
and in the correct way.
For that purpose, it is necessary to grasp the contents of any errors quickly and
accurately. Errors can be checked in three ways as explained below:
(1) Network diagnostics with GX Developer
(2) Confirmation by error code: Refer to Section 8.3
(3) Confirmation by the LED displays on the front of the network
(4) Confirmation of the error history of the entire system (Refer to
8 - 1
(a) Network monitor (Refer to Section 8.1)
The status of the following four types of networks can be checked by
monitoring the line:
1) Status of the entire network: Host information
2) Data link status and parameter status, etc. of each station:
Other station information
3) Control station information, detailed data link information, etc.:
Network monitor details
4) Loop switch count, line error, communication error, etc.:
Error history monitor
(b) Diagnostic tests (Refer to Sections 4.8 and 7.8)
The following five items can be checked or executed through the diagnostic
tests:
1) Wiring status (IN/OUT, etc.) of the data link cable:
Loop test (required for optical loop)
2) Setting status of numbers: control station/remote master station
duplication, network numbers and group numbers: Setup confirmation
test
3) The order of stations connected in the direction of the forward loop and
the reverse loop: Station order check test
4) Setting status of the routing parameters: Communication test
5) Link startup/stop for the host, specified stations and all stations:
Network test
When either cyclic transmission or transient transmission using dedicated link
instructions or GX Developer (communication with other stations) was not normally
performed, an error code is stored in the link special register and the system monitor.
The contents of the error can be checked by this error code.
module (Refer to Section 4.2)
With the LED displays, the following errors can be checked: whether the host is
operating or stopped, whether the station acts as a control station or a normal
station, whether the baton pass is being executed, whether data linking is being
executed, whether data is being transmitted/received, and whether any error has
occurred.
Section 8.3)
By using GX Works 2, error history of the entire system can be checked even
after errors were cleared by powering on and then off the programmable
controller or by resetting the programmable controller CPU.
REMARKS
In order to fix the errors that may have occurred during data linking quickly and
efficiently, it is important to perform offline tests of the network module and check the
data link cable when starting up the system.
Make sure to perform the following checks, which are explained in Chapter 4, "Setup
and Procedures Before Starting the Operation."
1) Standalone operation check and operational setting of the network module
2) Offline tests:
Hardware test, Internal self-loopback test, self-loopback test, station-to-station
test, and forward loop/reverse loop test (required for optical loop)
3) Check the connection of the data link cable.
MELSEC-Q
8
8 - 1