Memory Check Function - Mitsubishi Electric L02SCPU User's Manual And Reference

3.34

Memory Check Function

This function checks that data in the memories of the CPU module are not changed due to such as excessive electric
noise. Since the CPU module automatically checks a memory, setting for enabling this function is unnecessary. This
function does not require processing time.
(1) Data to be checked
(a) Program
The program during execution is compared with the user program written to the program memory. If they do not
match, a stop error, "RAM ERROR" (error code: 1160) is detected.
(b) Parameter
The parameters are compared with the ones written to the parameter-valid drive.
(c) Device memory
If the change of data in the device memory is detected, a stop error, "RAM ERROR" (error code: 1161) is
detected. For the LCPU whose serial number (first five digits) is "14012" or later, the device information, which
contains data change information, can be checked in SD927 and SD928. For details on the special register,
refer to the following.
MELSEC-L CPU Module User's Manual (Hardware Design, Maintenance and Inspection)
(2) Execution timing
• Program: At program execution
• Parameter: When the CPU module is powered off and on, when the CPU module is reset, and when the
CPU module is set from STOP to RUN after data are written to it
• Device memory: When device data are read
CHAPTER 3 CPU MODULE FUNCTIONS
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