Addressing external i/o – Rockwell Automation 1747-PTxx Getting Started Guide for HHT User Manual
Page 21
Chapter 2
Control Basics
2–4
As pointed out in the last section, external inputs and outputs are linked to
the input data file and output data file of the program. Each status bit in
these files has an address. You specify the appropriate address when you
enter an instruction in your ladder program.
For our purposes, input addresses have the form
I:e/b
where
I
= Input data file
:
= Element or slot delimiter
e
= Slot number of the input module
/
= Bit or terminal delimiter
b
= Terminal number used with input device
Similarly, output addresses have the form
O:e/b
where
O
= Output data file
:
= Element or slot delimiter
e
= Slot number of the output module
/
= Bit or terminal delimiter
b
= Terminal number used with output device
Examples:
I:1/0
= Input, slot 1, terminal 0
I:2/0
= Input, slot 2, terminal 0
O:3/0
= Output, slot 3, terminal 0
O:3/7
= Output, slot 3, terminal 7
O:0/7
= Output, slot 0, terminal 7 (fixed controllers only because of slot 0)
I:0/4
= Input, slot 0, terminal 4 (fixed controllers only because of slot 0)
Eventually, you will be addressing other data files, such as Status, Bit, Timer,
Counter, Integer, and Control. Addressing of these files is discussed in the
HHT User Manual.
Addressing External I/O