User Manual PLC-3 FAMILY I/0 Instruction Manual

DH and DH+ Communication
Chapter 4
4-11
Accessing a PLC-3 Processor from a PLC-2 Processor
While a PLC-3 controller can address any area of a PLC-2 data table, a
PLC-2 reads an input file that is a part of the PLC-3 data table. That file is
the PLC-3 input file with a number that corresponds to the station number
of the PLC-2 station. For example, the read/write files assigned to PLC-2
stations 1 to 100 (octal) is:
PLC2 compatible station number in octal Assigned input file for read/write access
000 I008
001 I001
002 I002
003 I003
004 I004
005 I005
006 I006
007 I007
010 I010
011 I011
012 I012
. .
. .
. .
077 I077
100 I100
Station address 000 is assigned to input file I008. Otherwise PLC-3 input
files with an 8 or 9 in their addresses are not used for read/write access by
a PLC-2 station.
The PLC-2 station can use either protected or unprotected commands to
access its assigned PLC-3 file. However, the PLC-2 station cannot access
its assigned file until that file is created and allocated at the PLC-3 station.
To create a file, refer to the user’s manual for your programming terminal.
You can have two PLC-3 stations communicate with each other as if they
were PLC-2 stations. To do this, allocate the appropriate PLC-2
addressing format (see chapter 5) in the assignment commands. Similarly,
a computer can send PLC-2 commands to a PLC-3 station by using the
appropriate message packet formats.