Yaskawa MP940-MW+ - Manual (Page 8)

TECHNICAL NOTE
MOTION PRODUCT AND ENGINEERING GROUP
Yaskawa Electric America - 2121 Norman Drive South – Waukegan IL 60085
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5/22/2003 8 of 34 eng/PubNumber/MCD
Fault Detection
After the start-up section has been completed successfully, the next section, and the
section that the program will be in most is the Fault Detection / Disable loop. All of the If Event
(including a special If Fault) blocks are designed to detect various faults and errors in the system.
When an error is detected, the next block that is executed is a Set Variable block that sets an
internal flag to trap the type of error that occurred and may also capture some pertinent data.
Lastly, Set Variable block (27) is executed, which sets an internal fault flag and clears the
SystemOk flag, then execution continues to disable handler. If the user simply turns off of the
enable input (Local_Input1), execution continues to disable handler. One thing to keep in mind is
that block 21 does not detect ServoPack warning conditions. ServoPack warning conditions
include any A.9x (where x = 0 – F) alarm code display on SGDH display. The programmer may
want to include additional code to detect these conditions and notify the operator. For example
A.91 is a torque overload warning, indicating that continued operation of the machine at this rate
will result in an A.71 or A.72 torque overload alarm.
Disable Handler
When a fault or a normal disable is detected, this section of code executed. The first
block (29) stores the commanded and actual position (these may be useful in a recovery routine).
Next, the other main programs are halted; the servo is commanded to go to zero speed (25), then
stop (26), and lastly the Servo Off block (8) is executed.