PLC Developments Increase Flexibility and Speed

 

New architectures are expanding capabilities, blurring the line between programmable automation controllers and PLCs.

Sureja priyesh

The programmable logic controller (PLC) was originally designed to replace hardwired systems composed of hundreds or thousands of relays, cam timers, drum sequencers, and dedicated closed-loop controllers. Updating these relay-based systems to accommodate changes and additions in the controlled machines and processes was a lengthy and expensive process, requiring electricians to add components and perform extensive rewiring. Troubleshooting was a nightmare, as problems could occur among thousands of connections, switch contacts, and hundreds or thousands of components.
Since the first PLC was developed in the 1960s, there have been enormous improvements to the technology in terms of speed of execution, programming methods, functionality, memory capacity, communications, and other areas.
This discussion will explore how advances in processing power have enabled PLCs to execute more functions in less time at lower cost, such that PLC functionality now often approaches programmable automation controller (PAC) power.

Leading advances of modern PLCs

1. Additional features incorporated in PLC CPU, eliminating external components

2. High-speed serial or Ethernet communications to remote wired or wireless I/O

3. Wide choice of I/O form factors

4. Custom functionality and faster execution, allowing PLC to take on more tasks

5. Advanced instruction reduce PLC programming time

6. Superior memory mapping improves data handling

7. Data structures simplify programming and maintenance

Table 1 summarizes, and the text below details, the leading advances of modern PLCs. But it’s important to note that no single PLC or PLC family incorporates all of the features listed. Rather, different products from various suppliers have various combinations of strengths and weaknesses, and no one product is the best fit for all applications. This means that end users must examine their applications carefully, and pick the PLC that offers the best selection of features and price for a particular application.