The combination of logic-driven control, a distributed architecture, and open standards gives Opto 22 control systems some distinct advantages, including efficiency, scalability, and the computing capacity for abilities far beyond control.īecause PLCs and Opto 22 systems are so different, it is easy to be misled by comparisons. Comparing PLCs and Opto 22 Control Systems Opto 22 systems, however, are built on open standards-not only automation standards such as OPC UA and Modbus, but also internet and IT (information technology) standards such as Ethernet, HTTPS, and MQTT. Most PLCs are part of proprietary systems built by one manufacturer and designed to be used with their own products. All of this distributed intelligence reduces the load on the controller. An I/O unit can also run multiple PID (proportional integral derivative) control loops independently. These functions include counting, latching, pulsing, frequency and period measurement, watchdogs, totalizing, minimum and maximum values, scaling, clamping, ramping, and more. The controller runs the control program, but an intelligent I/O processor in each I/O rack handles many functions independently. The values are fresh, and the controller doesn’t have to waste processing power continually scanning I/O.Īn Opto 22 control system also works differently from a PLC system because it utilizes a distributed architecture.

When logic requires I/O or variable values, an Opto 22 controller immediately gets only the values needed. An Opto 22 groov EPIC® (edge programmable industrial controller), a SNAP PAC (programmable automation controller), or even a legacy mistic controller (dating from the early 1990s) does not have to look at I/O or variables until the logic in the controller requires it. In contrast, Opto 22 controllers are logic-driven devices. Because a PLC works in this way, the speed of its scan time is a measure of its capability.

The loop scans all the PLC’s input points, solves the user logic program, and then sets all its outputs, over and over. A PLC’s CPU (central processing unit) is essentially a scanning device that runs a loop through every I/O point. The PLC (programmable logic controller) was developed to replace physical relays and timers with a purpose-built small computing unit designed for industrial environments. Although a great improvement over manual control, this type of automation structure had a major disadvantage: to change the function (or logic) of the control system, the system had to be literally re-wired. Banks of relays appeared in semi-automated factories, notably automobile plants. Industrial automation was originally implemented with discrete relays and timers, which were connected with copper wire.

Compare PLCs and Ladder Logic with Opto 22 Hardware and Software

Plc ladder logic program