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MELSEC-Q
7 FUNCTION
7.20.4 Restrictions
This section explains the items to be noted when the high speed interrupt function is
executed.
Depending on the items, a WDT error may occur or high speed interrupt may not be
executed at preset cycle intervals if the corresponding restrictions are not satisfied.
The restrictions are roughly classified into the following four different items.
(1) Items that are all disabled when high speed interrupt setting is made
(2) Items that are disabled only within high speed interrupt
(3) Items that hold high speed interrupt by interrupt disable
(4) Items to be noted in addition to (1) to (3)
The time taken to run an interrupt program once should not exceed the preset time of
the interrupt cycle interval. (If that time exceeds the preset time of the interrupt cycle
interval, high speed interrupt operation cannot be guaranteed.)
(1) Items that are all disabled when high speed interrupt setting is
made
No.
Item
Restriction
When Used
1
Q02CPU
No function for Q02CPU.
Parameter error is detected.
2
Base unit
QA1S6
B or QA6
B base is not
available.
Parameter error is detected.
3
Multiple PLC system
Multiple PLC system is not available.
Checked at parameter setting of GX Developer.
4
Instruction
PR/PRC, UDCNT1/2, PLSY, PWM, SPD,
PLOADP/PUNLOADP/PSWAPP
instructions are not available.
Any of the instructions indicated on left is not available
and error is detected.
5
Instruction
Instruction that will take longer
processing time than high speed interrupt
cycle is not available.
Since interrupt is disabled during instruction execution,
high speed interrupt is not available at preset cycle.
6
Programming unit
Programming unit is not available.
Response to instruction search will be slow, or
communication error may occur on programming unit
side.
7
SFC
The following two SFC functions are not
available.
1) SFC transition monitor check function
using SM90 to 99, SD90 to 99
2) Fixed-time executed block execution
function
Functions given on the left are not available and are
ignored.
8
Sampling trace
Time-based sampling trace is not
available.
(Sampling trace can be used every scan
or when detailed conditions are
executed.)
Sampling trace is not available and is ignored.
(When trace read is performed, data may not be set.)
9
Interrupt program (I0
to I48, I50 to I255),
fixed scan execution
type program
Interrupt program (I0 to I48, I50 to I255)
and fixed scan execution type program is
not available.
Since multiple interrupts are disabled, high speed
interrupt is not available at preset cycle while any
interrupt or fixed scan execution type program is run.
10
Online program
correction, online file
batch-write
Online program correction is not
available.
Online file batch-write is not available.
Since interrupt is disabled during online program
correction, a high speed interrupt start is delayed during
that period and therefore high speed interrupt is not
available at preset cycle.
(The following time is taken.
• Max. 102
s for online program correction
• Max. 300ms for online file batch-write)
11
File registers having
the same file name
as the program
name
File registers having the same file name
as the program name is not available.
Since interrupt is disabled when file registers having the
same file name as the program name are changed,
high speed interrupt is not available at preset cycle.
(The following time is taken.
• Max. 410
s for standard RAM
• 400
s + 100
s
number of program files for
SRAM card)
