27-03-2012, 03:07 PM
MICRO PLC
Basic PLC Training Material_Part2.ppt (Size: 748.5 KB / Downloads: 47)
Basic Training Review
What is a Control System?
What is a logic?
What is a PLC and its components?
How the information is getting integrated from plant floor to enterprise level?
What is a micro PLC?
What is Input Device, Output Device, CPU, Application Memory, Data, Operating Cycle(Scan Time), throughput time, Power Supplies, Programming Devices and HMI?
What are the similarity between Electrical Ladder Logic and Ladder Logic Program?
What are the different Ladder logic Instructions?
What are the fundamental logic rules for operation of logic?
What is a logic?
The first step involved in automating any industrial process or machine is to determine the sequence of operation or events which are specific to its operation. This sequence is then arranged into a set of logic functions.
Logic functions are of two types:
Combinatory: Where results depends only on the present state of the inputs.
Sequential: Where results depends on the present and past state of the inputs
Then this Logic scheme is turned into a physical system using the basic building blocks of the particular technology selected,i.e. Mechanical, Fluidic, Pneumatic, Electromechanical, Electronics.
What is a micro PLC?
Micro PLC’s are self-contained units with Processors,Power supply & I/O’s in one package …. Hence often called Packaged Controller.
General Characteristics are --
Number of Inputs and Outputs </= 32 I/O’s.
Cost in four figures.
Physical Size -- ever competing.
Ladder Logic Program
Ladder Logic closely resembles electrical ladder diagrams
A Ladder logic program exists only in the PLC’s software.
In ladder Logic it is not the actual flow of current thru circuits.
In electrical diagram the devices are described as open or closed(ON or OFF), where as in Ladder Logic, instructions are either TRUE or FALSE.
In Ladder Logic Program must contain at least one control instruction (output) and usually contains one or more conditions (inputs).