A Virtual Programmable Logic Controller |
|
|
Back to VLE Page
PLC Home A brief history Standards Applications Choosing a PLC Capabilities Principles of operation Hardware Programming and boolean operations Simulation 1 - Using the programming panel Simulation 2 - First steps in programming Simulation 3 - More complex networks Simulation 4 - Set/reset and impulse relay Simulation 5 - Using timers Simulation 6 - Using counters |
StandardsPLC manufacturers have, in the past, tended to develop their own proprietary systems rather than adhere to common industry standards. Systems can differ in hardware, operating system, programming language, and communication protocols. The IEC 65A (WG6) standard attempts to provide a specification for operational characteristics, but compatibility between competing vendors is not guaranteed, particularly in the areas of programming and communication. It is envisaged that PLCs will increasingly support a broad range of communications interfaces and protocols. |