
B-63434EN/02 DESCRIPTION 2.CYCLIC TRANSMISSION
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2.2 Common Memory Area 2 Cyclic Transmission
When the data of common memory area 2 is exchanged, DI areas
need to be set separately from DO areas.
In any case, a DI/DO area needs to be allocated in the PMC area
beforehand. If the setting of a DI/DO allocation area is changed, the
power needs to be turned off then back on. On the other hand, a part
of common memory area 2 can be dynamically changed by the user
program.
There are two allocation methods for DI areas: ① method for
dynamically changing DI data areas in node units and ② method for
statically fixing a DI data area independently of nodes.
2.2.1 DO data allocation
Procedure
Set the following parameters beforehand:
1) Pa13: Area 2 transmit data start address
2) Pa14: Area 2 transmit data size (in words)
3) Pa40: Allocation address (for DO)
4) Pa41: Data size (for DO) (in words)
5) Pa43: Area 2 data exchange condition allocation address
6) Pa44: Switch flag allocation address
Organization of area 2 data exchange condition allocation:
2222<, )'=$1+
2222< )**-:%/)+'-;
2222< ##-%>:%/)+'-;
2222<5 )**-:%/)+'-;
Note) This function does not use the hatched portions.
Procedure of dynamic change of common memory area 2 allocation
by the user program:
1) The user program specifies the following in the PMC D area
specified by Pa43 (area 2 data exchange condition allocation
address):
- DO offset
2) Then, the user program writes FFh to the area (switch flag) in
the PMC R area specified by Pa44 (switch flag allocation
address).
3) The CNC monitors the switch flag at all times. When FFh is
written, the node number, DI offset, data size, and DO offset set
in the PMC D area are taken in as internal information, and the
switch flag is set to 00h.