Mitsubishi 00JCPU User Manual page 331

(5) Precautions
(a) Maximum delay time of error detection
The following shows the maximum delay time from rewrite of program memory data till detection of the
rewritten data.
Maximum delay time
of error detection
*1: The maximum program memory capacity for each CPU module is shown below.
• 12PHCPU, Q12PRHCPU: 124K steps (124 1024 steps)
• Q25PHCPU, Q25PRHCPU: 252K steps (252 1024 steps)
The sequence program is executed until "RAM ERROR" is detected. Therefore, other errors may be detected
before "RAM ERROR" is detected or an unexpected operation may be performed due to corrupt data in the
program memory.
If "Capacity to be checked at one time" is set to "4" for the Q12PHCPU and the scan time is 10ms, the
maximum delay time is as shown below.
(124 1024)/(4 256) 10 = 1240 (ms)
If an user setting system area is set while the program memory is formatted, the program memory capacity will
reduce by the capacity set for the user setting system area.
For check methods of the user setting system area and program memory capacity, refer to Section 5.2.2.
(b) Instructions that cannot be used during memory check
If any of the following instructions is executed, "OPERATION ERROR" (error code: 4105) occurs.
• PLOADP instruction
• PUNLOADP instruction
• PSWAPP instruction
(c) Conditions to validate PLC parameters
After parameters set in the PLC parameter dialog box are written to the CPU module and either of the following
operations is performed, whether the memory check is performed or not can be selected.
• Powering off and then on the CPU module
• Resetting the CPU module
(d) Memory check during execution of the COM instruction
If the COM instruction is executed, the memory check will not be performed.
(Maximum program memory capacity)
=
(Capacity to be checked at one time)
CHAPTER6 FUNCTIONS
*1
(Scan time) (ms)
256
1
2
3
4
5
6
7
8
6 - 151