Rockwell Automation 1791-IOBB USER MANUAL - Manual (Page 10)

Introducing Block I/O
Chapter 2
2Ć3
Figure 2.3
Sourcing Output Example
DC Power
Supply
Field
Device
Field
Device
GND
+V
-V
Bus
Common
Fuse
Fuse
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Block I/O
You connect the block I/O to your remote I/O link as you would any other
device (Figure 2.4). The block looks like a 1/4 I/O rack to the processor,
and uses 2 words of input image table memory and 2 words of output
image table memory. The block is addressed directly on the remote I/O
link.
Block I/O functions exactly like any Allen–Bradley remote I/O product.
Input and output data is scanned asynchronously and transferred back and
forth between the block and the controller input and output image table.
Figure 2.4
Block I/O Connection in a PLC System
Blocks are daisy-chained to
a programmable controller
or a scanner.
Block I/O - each block
is 1/4 I/O rack.
Programmable Controller
or Scanner.
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