Rockwell Automation 1771-KA2 Communication Adapter Module - Manual (Page 57)

Communication Zone Rungs
Chapter 5
5-5
(Note that memory access rungs are not needed to allow unprotected
commands; only protected commands require a memory access rung.)
A memory access rung is composed of one or more memory access
branches, as shown in Figure 5.3.A. In this format, a BRANCH START
precedes a group of 3 GET instructions. The first GET instruction address
is the station number of a remote station. The next 2 GET addresses
define the word boundaries of the accessible data table area in the local
station processor. The specified remote station may control any bit or
word within three boundaries through protected commands.
Figure 5.3.B. illustrates the memory area that is now accessible to
protected commands from remote station 010, due to the memory access
branch of Figure 5.3.A.
Multiple memory access branches can be listed in a single memory access
rung. Each group of 3 GET instructions must be preceded by a BRANCH
START instruction. (This is true in all cases, even when only one
memory access branch is defined.) BRANCH END instructions can be
used to fit the memory access rung into the ladder diagram-display
format.
Use output instruction, OUTPUT ENERGIZE 02707, to fit the memory
access rung into the proper display format. (This output instruction has no
significance in memory access rung logic.)