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3.6.4
Remote latch clear
This function resets the latched device data from a programming tool when the CPU module is in the STOP status.
(1) Application
This function is useful in the following cases if used together with the remote RUN/STOP operation.
• When the CPU module is inaccessible
• To clear latched device data in the CPU module in a control panel externally
(2) Executing method
(a) Using a programming tool
Select [Online] [Remote Operation] "Latch clear".
(b) Using an external device in the MC protocol
Use the MC protocol command. For the commands, refer to the following.
MELSEC Communication Protocol Reference Manual
To perform the remote latch clear operation, follow the following steps.
1.
Change the operating status of the CPU module to STOP by the remote STOP operation.
2.
Clear the latched device data in the CPU module by the remote latch clear operation.
3.
After remote latch clear processing is completed, perform the remote RUN operation to return the
operating status to RUN.
(3) Precautions
(a) Latch clear in the RUN status
The latch clear operation cannot be performed when the CPU module is in the RUN status.
(b) Latch clear enabled range
There are two kinds of latch range can be set in the Device tab of the PLC parameter dialog box: latch clear
operation enable and disable range.
Remote latch clear operation resets only the data set in the "Latch (1)" (latch clear operation enable range).
For the method for resetting the device data in the latch clear operation disable range, refer to Page 75,
Section 2.7 (4) (b).
(c) Devices that are reset by the remote latch clear operation
Devices that are not latched are also reset when the remote latch clear operation is performed.
CHAPTER 3 FUNCTIONS
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