Lecture 2 Power Point Flashcards
Modular types use external I/O modules that plug into
The PLC
Input interface modules accept signals from the machine or process devices and
convert them into signals that can be used by the controller
Output interface modules convert controller signals
into external signals used to control the machine or process.
The remote rack is linked to the local rack through a pair of
communications modules
An address is a label or number that indicates where a certain piece of information is located
in memory.
Tag-based addressing is used with
Allen-Bradley
ControlLogix controllers
O:4/15
Output module in slot 4, terminal 15
I:3/8
Input module in slot 3, terminal 8
O:6.0
Output module, slot 6
I:5.0
Input module, slot 5
Every device connected to a discrete I/O module is addressed to a specific
bit in the PLC’s memory
A bit is a binary digit that can be either
1 or 0
Analog I/O modules use a
word addressing format
PC-based control runs on personal or industrial hardened computers. Also known as
soft PLCs, they simulate the functions of a PLC on a PC
Combination I/O modules can have both input and output connections
in the same physical module
An I/O module is made up of a printed circuit board and
and a terminal assembly.
The printed circuit board contains
electronic circuitry.
The terminal assembly is used for making
field-wiring connections
Most PLC modules have plug-in wiring terminal strips that plug into
the actual module
If there is a problem with a module, the entire strip is removed, a new module is inserted, and the terminal
block is plugged into the new module.
