Rockwell Automation 1785-Lxxx Enhanced and Ethernet PLC-5 Programmable Controllers - Manual (Page 108)

Publication 1785-UM012D-EN-P - July 2005
7-10 Communicating with a PLC-5 Adapter Channel
Programming Discrete
Transfers
in Adapter Mode
Typically, each output instruction in one controller should have a
corresponding input instruction in the other controller. The rack number of
the adapter mode controller-channel determines the addresses that you use.
Programming
Block-Transfers
of Data to an Adapter
Channel
Adapter-mode block-transfers are essentially continuous. As soon as a transfer
is completed, another block-transfer occurs immediately in the adapter-mode
controller; it then waits (with a buffered snap-shot of data) for the supervisory
controller to perform another block-transfer request. Therefore, the data that
is transferred after the request is data from the previous transfer. If the
supervisory controller performs a block-transfer request from the
adapter-mode controller every 500 ms, for example, the data is at least 500 ms
old.
The supervisory controller contains the ladder-logic transfer instructions
which controls the actual communication transmission. However, the
adapter-mode controller channel controls the:
• actual number of words of data that is transferred
• data table location from which the data is transferred
17
16
N51:15
15
N51:05
14
Supervisory Processor (PLC-5) Adapter-mode Processor Channel
0:x7
I:x5
N51 is the adapter-mode processor's discrete transfer configuration file. Input destination and output source
entries determine input and output words.
The ladder logic in the supervisory processor uses the rack number of the adapter-mode processor channel.
Condition the ladder logic in the adapter processor with the status bits (page ).
N51:15
8 9 11 13
13 17
I:x5
IMPORTANT
Do not use ladder-logic block-transfer instructions for the
adapter-mode controller channel; you configure the
block-transfers from channel configuration screens and
data monitor screens.