Rockwell Automation 1771-IFE , D17716.5.90 USER MNL. ANALOG INPUT Module - Manual (Page 55)

Appendix
D
D-1
Block Transfer (MiniĆPLCĆ2 and PLCĆ2/20
Processors)
Programming multiple GET instructions is similar to block format
instructions programmed for other PLC-2 family processors. The data table
maps are identical, and the way information is addressed and stored in
processor memory is the same. The only difference is in how you set up
block transfer read instructions in your program.
For multiple GET instructions, individual rungs of ladder logic are used
instead of a single rung with a block transfer instruction. A sample rung
using multiple GET instructions is shown in Figure D.1 and described in
the following paragraphs.
Rung 1: This rung is used to set four conditions.
Examine On Instruction (113/02) - This is an optional instruction.
When used, block transfers will only be initiated when a certain action
takes place. If you do not use this instruction, block transfers will be
initiated every I/O scan.
First GET Instruction (030/120) - identifies the module’s physical
address (120) by rack, group and slot; and where in the accumulated
area of the data table this data is to be stored (030).
Second GET Instruction (130/060) - indicates the address of the first
word of the file (060) that designates where the data will be transferred.
The file address is stored in word 130, 100
8
above the data address.
Output Energize Instruction (012/07) - enables the block transfer read
operation. If all conditions of the rung are true, the block transfer read
enable bit (07) is set in the output image data table control byte. The
output image table control byte contains the read enable bit and the
number of words to be transferred. The output energize instruction is
defined as follows:
“0” indicates that it is an output instruction
“1” indicates the I/O rack address
“2” indicates the module group location within the rack
“07” indicates this is a block transfer read operation (if this were a block
transfer write operation, “07” would be replaced by “06”.)
Multiple GET Instructions Ć
MiniĆPLCĆ2 and PLCĆ2/20
Processors