Technical articles on Electronics and Electrical Engineering topics focused on Basics of EE, Electronic components, power systems and equipment used for generation, transmission, operation, and controls of electricity.
Input/output capability for programmable logic controllers comes in three basic varieties: discrete, analog, and network. A “discrete” data point is one with only two states on and off. Process switches, pushbutton switches, limit switches, and proximity switches are all examples of discrete sensing devices. In order for a PLC to be aware of a discrete … Read more
Some low-end PLCs are strictly monolithic, with no ability to accept additional I/O modules. This General Electric Series One PLC (used to monitor a small-scale hydroelectric power generating station) is an example of a purely monolithic design, having no “expansion” slots to accept I/O cards: A disadvantage of monolithic PLC construction is that damaged I/O … Read more
Koyo “CLICK” PLC series belongs to class of smaller PLCs. While the Siemens S7 and Rockwell ControlLogix PLC platforms represent large-scale, modular PLC systems, there exist much smaller PLCs available for a fraction of the cost. Perhaps the least expensive PLC on the market at this time of writing is the Koyo “CLICK” PLC series, … Read more
A modern PLC manufactured by Allen-Bradley (Rockwell) is this ControlLogix 5000 system, shown in this photograph used to control a cereal manufacturing process. The modular design of the ControlLogix 5000 system follows the more traditional scheme of individual cards plugged into a rack of fixed size: Article from Lessons In Industrial Instrumentation by Tony R. … Read more
A modern PLC manufactured by Siemens appears in this next photograph, an S7-300, which is a different design of modular PLC. Instead of individual cards plugging into a rack, this modular PLC design uses individual modules plugging into each other on their sides to form a wider unit: Article from Lessons In Industrial Instrumentation by … Read more
A newer model of PLC manufactured by Allen-Bradley is the SLC 500 series (often verbally referred to as the “Slick 500”), which is also modular in design like the older PLC-5 system, although the racks and modules of the SLC 500 design are more compact. The SLC 500 rack shown in the next photograph has … Read more
The photograph below shows an Allen-Bradley (Rockwell) PLC-5 system, used to monitor and control the operation of a large natural gas compressor. Two racks appear in this first photograph, with different types of I/O cards plugged into each rack: Like the Siemens 505 PLC seen previously, this Allen-Bradley PLC-5 system is fully modular and configurable. … Read more
The photo below shows a Siemens (Texas Instruments) 505 series PLC, installed in a control panel of a municipal wastewater treatment plant. This is an example of a modular PLC, with individual processor, I/O, and communication cards plugged into a rack. Also Read: Difference between Modular and Monolithic PLCs (Top 10 Differences) Three racks appear … Read more
All PLCs can be generally categorized into two types: Modular and Monolithic PLCs. Feature Modular PLCs Monolithic PLCs Size Large Small Construction Consist of a rack into which circuit “cards” are plugged Consist of a monolithic “brick” containing all processor, I/O, and communication functions Cost Expensive Cheap I/O Capability Comprises of racks where ample number … Read more
Coal-fired power plants or coal-fired power stations utilized heat energy coal to make steam in order to generate electricity. The video below illustrates the working of coal power plants.