Mitsubishi Q00CPU, Руководство пользователя

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- 206 6.28 Memory Check Function
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FUNCTIONS
(5) Precautions
Note the following items when executing memory check on the Process CPU and
Redundant CPU.
(a) Maximum delay time for detecting errors
From the start of rewriting the program memory data to detecting the rewritten
data, maximum delay time will occur as the following expression.
The sequence program continues to execute before the program memory check
detects errors.
There is a possibility that the program memory check detects other errors before
detecting RAM ERROR or causes an unexpected operation due to erroneous
program memories.
For example, when setting a check capacity 4 in Q12PHCPU at one time, the
maximum delay time will be (124 1024) (4 256) 10=1240(ms).
* 2 : The maximum capacity of program memory in each CPU modules is shown below.
Q12PHCPU, Q12PRHCPU: 124k steps (124 1024 steps)
Q25PHCPU, Q25PRHCPU: 252k steps (252 1024 steps)
If a user setting system area is set at formatting a program memory, the capacity
of the program memory will decrease for the set capacities of the user setting
system area.
For a user setting system area and confirmation methods for a capacity of
program memories, refer to Section 5.2.2.
* 3 : Indicates "Capacity to be checked at one time" set in "PLC RAS(2)" tab in Qn(H) Parameter
the dialog box. ( (2)in this section)
Maximum delay time for detecting errors = (Scan time)
(Maximum capacities of program memories)
(Capacities to be checked at one time)* X 256
X
(ms)
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