Yaskawa MP900 Series Ladder Programming Manual - Manual (Page 373)

7.4 Detailed Troubleshooting
7.4.3 Watchdog Timer Errors
7-10
7.4.3 Watchdog Timer Errors
Watchdog timer errors can be caused by the following problems.
• An infinite loop occurs in a user program.
• The scan time is exceeded by a user program.
• A Motion Module *1 fails.
• A watchdog timer error occurs in an MPU-01 Module.
*2
∗ 1. Motion Modules: PO-01, SVA-01, SVB-01, SVC-01, and MPU-01
∗ 2. If a watchdog error occurs when you are using an MPU-01 Module, refer to Chapter 6 Troubleshooting in the
Machine Controller MP2000 Series MPU-01 Multiple-CPU Module User’s Manual (Manual No.: SIEP
C880781 05).
If a watchdog timer error occurs, it is important to determine if the cause of the error is in the CPU Module or in a
Motion Module.
To determine where the cause of the error was, stop the programs in the CPU Module and then restart the CPU Module
to see if the problem changes.
If a watchdog timer does not occur when the programs in the CPU Module are stopped, it is very likely that the cause
of the error is in the CPU Module. Check the programs to see if there are any infinite loops.
If this does not solve the problem, then there is a chance that the Motion Module is faulty. Consult with your Yaskawa
representative.
7.4.4 Module Synchronization Errors
Module synchronization errors can be caused by the following problems.
• A Motion Module
*1
fails.
• A watchdog timer error occurs in an MPU-01 Module. *2
∗ 1. Motion Modules: PO-01, SVA-01, SVB-01, SVC-01, and MPU-01
∗ 2. If a Module synchronization error occurs when you are using an MPU-01 Module, refer to Chapter 6 Trouble-
shooting in the Machine Controller MP2000 Series MPU-01 Multiple-CPU Module User’s Manual (Manual
No.: SIEP C880781 05).
If a Module synchronization error occurs (i.e., if SW00050 = 0051 hex), the slot where the Module synchronization
error was detected is reported in the system registers given in the following table.
∗ Module synchronization errors are reported for CPU Modules with a system software version of 2.75 or higher.
For version 2.74 or lower, it is reported as a watchdog timer error.
If a Module synchronization error occurs, consult with your Yaskawa representative.
STOP
SUP
INIT
CNFG
MON
TEST
SW1
OFF ON
1 2 3 4 5 6
Turn ON the STOP switch on the front panel of the CPU Unit
and then turn the power supply OFF and ON again to start the
CPU Module without executing the ladder programs in the
CPU Module.
Register Address Description
SW00076
Slot where Module synchronization error was detected *
xxyy hex: xx: Rack number (01 to 04), yy: Slot number (01 to 09)