by Armando Chacon | Jan 3, 2021 | Control Engineering
Memory is the element that stores information, programs, and data in a PLC. The user memory of a PLC includes space for the user program as well as addressable memory locations for storage of data. Data are stored in memory locations by a process called writing. Data...
by Armando Chacon | Dec 31, 2020 | Control Engineering
Many different types of I/O modules have been developed to meet special needs. HIGH-SPEED COUNTER MODULE The high-speed counter module is used to provide an interface for applications requiring counter speeds that surpass the capability of the PLC ladder program....
by Armando Chacon | Dec 27, 2020 | Control Engineering
Discrete devices are inputs and outputs that have only two states: on and off. In comparison, analog devices represent physical quantities that can have an infinite number of values. Typical analog inputs and outputs vary from 0 to 20 milliamps, 4 to 20 milliamps, or...
by Armando Chacon | Dec 25, 2020 | Control Engineering
The most common type of I/O interface module is the discrete type. This type of interface connects field input devices of the ON/OFF nature such as selector switches, pushbuttons, and limit switches. Likewise, output control is limited to devices such as lights,...
by Armando Chacon | Dec 21, 2020 | Control Engineering
The input/output (I/O) section of a PLC is the section to which all field devices are connected and provides the interface between them and the CPU. Input/output arrangements are built into a fixed PLC while modular types use external I/O modules that plug into the...
by Armando Chacon | Dec 14, 2020 | Control Engineering
The criteria used in categorizing PLCs include functionality, number of inputs and outputs, cost, physical size, and in some cases the brand requirements from the client. You can look as example the omron table for selecting a PLC. Of these, the I/O count is the most...
