Rockwell Automation 1771-OFE/B Analog Output Module User Manual - Manual (Page 71)

Appendix
B
Publication 1771Ć6.5.30 - November 1998
Block Transfer with 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 write 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 B.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) to which or from which the data is
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 that the module is in the lower slot and that this
is a block transfer read operation (if this were a block transfer
write operation, “07” would be replaced by “06”).
Important: The OUTPUT ENERGIZE Address 012/07 in this
example indicates that the module is in Slot 0. The
address could be 012/17, which indicates that the
module is in Slot 1 (012/06 or 012/16 for a write
operation).
Multiple GET Instructions