Rockwell Automation 1775-KA PLC-3 Communication Adapter Module User Manual - Manual (Page 63)

Addressing Rules and Examples
Chapter 4
4Ć7
The PLC–3 processor uses logical addresses to reference data in memory.
No PLC–3 address is valid unless it memory location has been allocated.
You can allocate memory by using the CREATE command in PLC–3
programming. The PLC–3 Programming Manual (publication 1775–6.4.1)
explains how to do this. Note that the CREATE command for memory
allocation is different than the CREATE command for creating symbolic
addresses (Chapter 6).
The following rules apply when specifying a PLC–3 logical address in a
message procedure:
1. Symbolic addresses must be defined to either the word level or the
file level of specification.
2. A word address may be either: (a) a block address specified to the
word level, (b) a symbolic address of a word, or (c) a symbolic file
address followed by a colon (:) and an offset.
3. A size specification must be preceded by a word address and a
comma (,).
4. An offset specification must be preceded by a file address and a
colon (:).
5. A bit number must be preceded by a word address and a slash (/).
6. To access the pointer or floating point sections of memory, extended
addressing must be used.
These rules are applied in the formats given below for addressing PLC–3
data locations.
Addressing a File
The format for addressing a PLC–3 file is one of the following:
<fileaddr>
<flesym>
For assignment commands that copy data from one file to another, both
the source and the destination file must be exactly the same size.
PLC-3 Address Specifications