Omron SYSMAC C200HS Operation Manual page 266

Subroutines and Interrupt Control
Data Concurrence
256
The PC Setup for the C200HS contains settings in DM 6620 that disable refresh-
ing in the normal cycle for specific Special I/O Units. This settings are as shown
below.
DM6620
Bit 15
1
Interrupt mode
(1 = high-speed)
Note Disabling special I/O refreshing in the normal cycle to refresh special I/O in an
interrupt subroutine is necessary only in the high-speed mode. Disabling normal
cycle refreshing of special I/O during normal interrupt mode will be ignored and
the special I/O will be refreshed both in the normal cycle and in the interrupt sub-
routine.
The execution time of interrupt subroutines must be kept to less than10 ms if the
high-speed interrupt mode is used and Special I/O Units, Host Link Units, or Re-
mote I/O Units are programmed. An interrupt programming error (system FAL
error 8B) will occur if the execution time is 10 ms or greater.
The execution time of interrupt subroutine with the longest execution time is out-
put to SR 262 and the number of the subroutine with the longest execution time
is output to SR 263.
Example: 12.3 ms for subroutine #80
0
SR 262
SR 263
8
Note The above 10-ms limit does not apply when the normal interrupt mode is used or
when the above Units are not mounted.
Although data concurrence is not a problem for execution of normal arithmetic
instructions or comparison instructions, it can be a problem when executing
longer instructions that handle multiple words, such as block transfer instruc-
tions, when the high-speed interrupt mode is used and the same data is handled
both in the main program and in an interrupt subroutine.
Data may not be concurrent in two different situations: 1) if a data write operation
in the main program is interrupted and the same data is read in an interrupt sub-
routine and 2) if a data read operation in the main program is interrupted and the
same data is written in an interrupt subroutine.
12
0 0 * * *
1 2 3
Maximum interrupt subroutine execution time (in 0.1 ms)
No. of interrupt subroutine with maximum execution time
0 * *
Section 5-23
* * * * * * *
00
Unit #0
Unit #1
.
.
.
Unit #9