Types of PLC and Specification

Classification or Type of PLC

What is a Programmable Logic Controller? Write its technical definition. ⬅️

Fixed input /Output PLC -

A fixed PLC is made up of fixed or built-in input and output sections. Input / output and wilt-in of this type of fixed PLC are irreversible. It consists of a fixed, built-in and non-removable screw terminal strip that incorporates screw terminals connections and all outputs of all types of input signals. It consists of a plastic gate of the input terminals on the leveled region which is located upwards. Opening this gate displays all the built-in input screw terminals. The leveled plastic gate is located downstream from the output terminals. Opening this gate displays all the built-in output screw terminals. Fixed input / output PLC is displayed in Fig.

Fixed Input / Output PLC

It consists of two fixed PLCs, Nano and Micro. The Nano PLC is a small size PLC with a memory capacity of 16 Kb less than the RAM. It consists of 16 PLC micro PLC fixed PLCs with input / output memory capacity up to a few Kb, with 32 / O. This type of PLC consists of the power supply, the processor, the I / O modules and the memory itself. These are also known as packaged controllers. They are small in size and of little value, so they can be easily installed and purchased.

Modular Input/Output PLC

The terminal unit is not built in the processor unit of the modular PLC. The input and output points in a modular PLC are called plug-in type removable. Inputs and outputs of the modular PLC are included with a chassis, rack, or baseplate, where the power supply is present to separate the CPU and hardware items of all input and output modules. The electrical connection between each module and the CPU is made by two mating plugs. A plug is thus attached to the PLC module Which is used to transfer signals from the module to the CPU. Others are used for clipping on the baseplate so that it cannot slide on the rack and chassis

The power supply is modular, line voltage and hooked up to the right or left or any other position on the rack or chassis. The CPU is installed in the right or left position next to the power supply. It is specifically a plug-in module. These are medium size and large PLC modular. Inputs / outputs of medium-sized PLCs are calculated to be less than 1024 Kb and large-sized PLCs count more than 1024Kb. The diagram shows the modular input / output PLC

Modular input / output PLC

(A) PLC (Small PLC)

Less than 100 input and output ports are created by designing a small PLC. It has local input with 20 input and 12 output port processors. In this type of design, additional input / outputs are added from the racks to the acmodate with the help of a remote. This type of PLC2 can store logical programs from Kb to 10 Kb.

(B) PLC Medium PLC

This type of PLC includes instruction sets, such as mathematical functions, file functions, and PID process controls. These types of PLCs have between 4000 and 8000 inputs and outputs. These are made for the elements of special modules, such as ASCII communication modules, BASIC programming modules, 16-bit multiplexing modules, analog input and output modules and communication modules, etc.

(C) PLC (LARGE PLC)

Large PLCs have been designed to provide adequate memory specification to the entire industries automation. However, its main disadvantage is that when the industry shuts down, the PLC performs dysfunctionality. In this type of system, the local area network is used in distributed controls and a fixed network is generated by interconnecting small PLCs. In this way different PLCs are used in an industry and a certain part of it is not allowed to be affected by the PLC as the entire systone spreads.

Specifications of PLC

(i) I/O Specifications

Number of I/O channels
AC / DC inputs
Sync / source type input
output relay rating (120 V AC, 2.5A)
Isolated relay output

(ii) Throughput – Time input is the time required to energize the sensor and its corresponding output. For example, a 500 instruction program requires a time of 1.85 ms as its throughput

(iii) Memory Capacity - PLC's memory capacity is a few kilo words

(iv) Scan Time - The scan time of the PLC is a few seconds

(V) Execution Speed - The PLC's speed execution per step is a few micro seconds

(Vi) Compatibility -