Omron CJ1G-CPU series, Programming Manual

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Peripheral Servicing Priority Mode Section 6-9
Auxiliary Area Information If the slice times are set for program execution and peripheral servicing, the
total of all the program execution and peripheral servicing slice times will be
stored in A266 and A267. This information can be used as a reference in
making appropriate adjustments to the slice times.
When Peripheral Servicing Priority Mode is not being used, the program exe-
cution time will be stored. This value can be used in determining appropriate
settings for the slice times.
6-9-2 Temporarily Disabling Priority Mode Servicing
Data concurrence is not guaranteed at the following times if Peripheral Servic-
ing Priority Mode is used.
• When more than one word is read from a peripheral device using a com-
munications command. The data may be read during different peripheral
servicing time slices, causing the data to not be concurrent.
• When instructions with long execution times are used in the program,
e.g., when transferring large quantities of I/O memory data. The transfer
operation may be interrupted for peripheral servicing, causing the data to
not be concurrent. This can be true when words being written by the pro-
gram are read from a peripheral before the write has been completed or
when words being read by the program are written from a peripheral
before the read has been completed.
• When two instructions access the same words in memory. If these words
are written from a peripheral device between the times the two instruc-
tions are executed, the two instructions will read different values from
memory.
When data concurrence must be ensured, the DISABLE INTERRUPTS and
ENABLE INTERRUPTS instructions (DI(693) and EI(694)) can be used for
CS1 or CJ1 CPU Units to prevent priority servicing during required sections of
the program, as shown in the following example. For CS1-H, CJ1-H, or CJ1M
CPU Units, the DISABLE PERIPHERAL SERVICING and ENABLE PERIPH-
ERAL SERVICING instructions (IOSP(287) and IORS(288)) can be used
Words Contents Meaning Refreshing
A266 and A267 00000000 to
FFFFFFFF Hex
(0 to 4294967295
decimal) The contents is
refreshed each cycle
and is cleared at the
beginning of opera-
tion.
Total of all slice times for program execution and
all slice times for peripheral servicing.
0.0 to 429,496,729.5 ms (0.1-ms increments)
Value is stored
as 32-bit binary
(8-digit hexadeci-
mal) value
A267
(Most-signifi-
cant bytes) A266
(Least-signifi-
cant bytes)
Priority servicing will not be executed between DI(693) and
EI(694) while W000000 is ON.