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Programmable Logic Controllers (PLCs) have considerably changed industrial automation by allowing for a great deal of flexibility and making it easier to develop and implement complex logic for advanced automation. PLC-based control panels are also significantly smaller than relay-based ones and can use touch LCD (HMIs) that replace rows and rows of light indicators. The ability to interface with analog sensors was also expanded with the advent of the PLC.....

Posted by Admin

When PLCs were first introduced, they were limited to ladder logic. Communication with other systems via RS232, RS485 and TCP/IP did not exist and neither did scripts to develop advanced mathematical algorithms for data processing. So there was a phase where several companies developed custom microprocessor based controllers which allow them to hard code some of these missing features from the PLC. We at one point had own microprocessor based circuit board for automation applications. The latest version had a touch LCD,TCP/IP and some other advanced features. This is actually a simple system to develop, a micro-controller, few transistors, some relays along with other components, and a few hundreds of line of code and voila; automation the size of a matchbox! Is this the future?...

Posted by Admin

Some of us remember using RS232 at 9600 baud or slower. At that time, RS232 was very popular and was used in many field. When it came to multi-node communication, RS485 was the alternative to RS232. Modbus, Device net, RIO, CAN, J1850, are some of the protocols that were used and some are still used in automation, automotive and several other industries.
Efficiently and properly communicating over these physical layers requires the use of a layered protocols. In the automation and controls areas, the communication protocol layers are transparent to the end user. Configuring the node addresses along with a few parameters is often as complicated as it gets. However, what if there is a need for a custom communication protocol. Will the PLC be the stumped?