Rockwell Automation 1770, D17706.5.16 Ref Mnl DF1 Protocol Command - Manual (Page 225)

13–10 PLC Addressing
Publication 1770Ć6.5.16 - October 1996
PLCĆ5 Logical Addressing
PLC-5 processors, like PLC-3 processors, use a form of logical
addressing. With logical addressing, you specify the address for
each level (or sub-division) of PLC-5 memory, down to the smallest
subdivision you want to access:
With this processor You can specify up to
PLCĆ5 4 levels of extended addressing, which is enough to address
any word in PLCĆ5 memory.
PLCĆ5/250 7 levels of extended addressing, which is enough to address
any word in PLCĆ5/250 memory.
To send a command message to a PLC-5 node, you put the extended
address of the node in the field labelled PLC-5 SYSTEM ADDRESS
in the message block formats of your program. (See Chapter 7,
“Communication Commands.”) There are two types of PLC-5
logical addressing:
Logical Addressing
Type
Processors Description Page
logical binary
addressing PLCĆ5 A series of bytes used to encode up
to 4 levels of an address.
13-11
addressing
PLCĆ5/250 A series of bytes used to encode up
to 7 levels of an address.
13-13
logical ASCII
addressing
PLCĆ5 and
PLCĆ5/250
UserĆspecified address in the same
form that you use at the programming
node.
This addressing lets any device
communicate with any other device,
without knowing the internal memory
structure of the target device.
13-15