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Peripheral Servicing Priority Mode Section 6-9
• The setting cannot be made from the CX-Programmer for CS1 or CJ1
CPU Units. The setting can be made from CX-Programmer Ver. 2.1 or
higher for CS1-H and CJ1-H CPU Units.
Note If an error is detected in the PLC Setup, A40210 will turn ON and a non-fatal
error will occur.
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 mak-
ing 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 oper-
ation may be interrupted for peripheral servicing, causing the data to not
be concurrent. This can be true when words being written by the program
are read from a peripheral before the write has been completed or when
Conditions CPU Unit operation PLC Setup errors
Time Slice for
Peripheral
Servicing
Time Slice for
Instruction
Execution
Specified Units
and Ports
01 to FF: (0.1 to
25.5 ms)
05 to FF: (5 to
255 ms)
All correct settings Peripheral Servicing Priority
Mode
None
00 and correct set-
tings
Correct, but redun-
dant settings
Some illegal set-
tings
Peripheral Servicing Priority
Mode for items with correct
settings
Generated
All 00 settings Normal operation Generated
00 and illegal set-
tings
All illegal settings
00 00 --- Normal operation None
Any other --- Normal operation Generated
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.
0.0 to 429,496,729.5 ms (0.1-ms increments)
Total of all slice times for program execution
and all slice times for peripheral servicing.
Value is stored
as 32-bit binary
(8-digit hexadeci-
mal) value
A266
(Least-signifi-
cant bytes)
A267
(Most-signifi-
cant bytes)
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