
B-64164EN/01 SPECIFICATION 2.CYCLIC TRANSMISSION
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2.2.2.4 Timing of switching between conditions on data exchange
with common memory area 2
In data exchange between common memory area 2 and the PMC area,
the user can switch between data (nodes information) exchange
conditions.
The timing of data switching specified by the user program is
described below.
User program System
(1) Sets each parameter in the
PMC D area specified by
Pa43.
(2) Sets FFh in the switch flag
specified by Pa44.
(3) Checks that the switch flag is
set to FFh.
(4) Reads each parameter from
the PMC D area specified by
Pa43.
(5) Exchanges data under a new
data exchange condition.
(7) Checks that the switch flag
is set to 00h.
(6) Sets 00h in the switch flag.
(8) Performs data processing.
Performs data exchange under
the new data exchange condition
from this point and up.
CAUTION
1 If the setting of a parameter in the PMC D area
specified by Pa43 (allocation condition setting (for
DI/DO)) is incorrect (for example, if a specified DI
offset exceeds the common memory area of a
specified node number), data exchange is not
performed. So, be careful when making a data
exchange condition modification.
2 Do not access the DI data of common memory
area 2 until the switch flag is set to 00h after the
switch flag is set to FFh by the user program.
Otherwise, invalid data may be read.
NOTE
Immediately after the power is turned on, data
exchange is performed according to each
parameter set in the PMC D area specified by
Pa43 (allocation condition setting (for DI/DO)) even
if no instruction is provided by the user program.