Rockwell Automation 1771-IS 5V DC INPUT MOD - Manual (Page 33)

Programming and Operation
Chapter 3
3-14
Important: The 12-bit data position (switch #2 OFF) should be selected
when 3-digit thumbwheel switches are used. Otherwise switch status data
from this device can become scrambled when transferred to the data table.
Switch status data can be transferred to the PC processor data table by
using block transfer instructions.
The Mini-PLC-2/15, PLC-2/30 and PLC-3 programmable controllers use
block transfer instructions. The Mini-PLC-2 (1772-LN3 Processor) and
PLC-2/20 use multiple GET instructions for programming block transfer.
Block Transfer Programming, PLC-2 Family
The processor transfers switch status data from the module to the data
table by a block transfer read operation. The following information must
be specified in order to program block transfer, whether using block
transfer instructions or multiple GET instructions. Values entered in
parentheses correspond to the programming example in paragraph titled
“Programming Example, PLC-2 Family” and Figure 3.8.
a) block length: the number of words to be transferred can be 0-7
depending on the number of switch assemblies. (03)
b) module address: rack, module group and slot number. (121)
c) data address: contains the module address in binary coded decimal
and is the first available address in the timer/counter accumulated area
of the data table. (030)
d) file address: defines the first of a group of words in the data table to
receive the transferred data and is located 100
8
above the data address.
(060)
For additional information on programming block transfer instructions,
refer to paragraph titled “Programming Considerations, PLC-2 Family”
and the Programming and Operations manual for the processor being
used.
Block Transfer of Switch Data