Quite complex systems can be created with networks of these controllers communicating using industry standard protocols. Networking allow the use of local or remote SCADA operator interfaces, and enables the cascading and interlocking of controllers. However, as the number of con
FUJIAN Xiamen ZheXun Electric Automation Co., Ltd. [2020-04-15 16:25:06 ]
The simplest control systems are based around small discrete controllers with a single control loop
FUJIAN Xiamen ZheXun Electric Automation Co., Ltd. [2020-04-15 16:24:24 ]
Larger systems are usually implemented by supervisory control and data acquisition
FUJIAN Xiamen ZheXun Electric Automation Co., Ltd. [2020-04-15 16:23:43 ]
Industrial control system ( ICS ) is a general term that encompasses several types of control systems Such systems can range in size from a few modular panel-mounted controllers to large interconnected and interactive distributed control systems with many thousands of field conne
FUJIAN Xiamen ZheXun Electric Automation Co., Ltd. [2020-04-15 16:22:43 ]
A variant of PLCs, used in remote locations is the remote terminal unit
FUJIAN Xiamen ZheXun Electric Automation Co., Ltd. [2020-04-15 16:21:46 ]
In more recent years, [ when? ] small products called programmable logic relays (PLRs) or smart relays, have become more common and accepted. These are similar to PLCs and are used in light industry where only a few points of I/O are needed, and low cost is desired. These small d
FUJIAN Xiamen ZheXun Electric Automation Co., Ltd. [2020-04-15 16:20:55 ]
PLCs may include logic for single-variable feedback analog control loop, a PID controller
FUJIAN Xiamen ZheXun Electric Automation Co., Ltd. [2020-04-15 16:20:08 ]
Very complex process control, such as used in the chemical industry, may require algorithms and performance beyond the capability of even high-performance PLCs. Very high-speed or precision controls may also require customized solutions; for example, aircraft flight controls. Sin
FUJIAN Xiamen ZheXun Electric Automation Co., Ltd. [2020-04-15 16:19:29 ]
A microcontroller
FUJIAN Xiamen ZheXun Electric Automation Co., Ltd. [2020-04-15 16:18:50 ]
For high volume or very simple fixed automation tasks, different techniques are used. For example, a cheap consumer dishwasher
FUJIAN Xiamen ZheXun Electric Automation Co., Ltd. [2020-04-15 16:17:56 ]
PLCs are well adapted to a range of automation Programmable controllers are widely used in motion, positioning, or torque control. Some manufacturers produce motion control units to be integrated with PLC so that G-code
FUJIAN Xiamen ZheXun Electric Automation Co., Ltd. [2020-04-15 16:17:15 ]
In recent years \"safety\" PLCs have started to become popular, either as standalone models or as functionality and safety-rated hardware added to existing controller architectures ( Allen-Bradley
FUJIAN Xiamen ZheXun Electric Automation Co., Ltd. [2020-04-15 16:16:32 ]
Prior to the discovery of the Stuxnet
FUJIAN Xiamen ZheXun Electric Automation Co., Ltd. [2020-04-15 16:15:45 ]
As PLCs became more advanced, methods were developed to change the sequence of ladder execution, and subroutines were implemented. [22] This enhanced programming could be used to save scan time for high-speed processes; for example, parts of the program used only for setting up t
FUJIAN Xiamen ZheXun Electric Automation Co., Ltd. [2020-04-15 16:14:57 ]
There are 5 main steps in a scan cycle Reading inputs Executing the program Processing communication requests Executing CPU diagnostics Writing outputs A PLC program generally loops i e. executes repeatedly, as long as the controlled system is running. At the start of each execut
FUJIAN Xiamen ZheXun Electric Automation Co., Ltd. [2020-04-15 16:13:50 ]
PLCs use built-in ports, such as USB PLCs used in larger I/O systems may have peer-to-peer
FUJIAN Xiamen ZheXun Electric Automation Co., Ltd. [2020-04-15 16:13:02 ]
Some PLCs enforce a strict left-to-right, top-to-bottom execution order for evaluating the rung logic. This is different from electro-mechanical relay contacts, which in a sufficiently complex circuit may either pass current left-to-right or right-to-left, depending on the config
FUJIAN Xiamen ZheXun Electric Automation Co., Ltd. [2020-04-15 16:12:20 ]
The most basic function of a programmable controller is to emulate the functions of electro-mechanical relays. Discrete inputs are given a unique address, and a PLC instruction can test if the input state is on or off. Just as a series of relay contacts perform a logical AND func
FUJIAN Xiamen ZheXun Electric Automation Co., Ltd. [2020-04-15 16:11:37 ]
The functionality of the PLC has evolved over the years to include sequential relay control, motion control, process control
FUJIAN Xiamen ZheXun Electric Automation Co., Ltd. [2020-04-15 16:10:50 ]
The main difference from most other computing devices is that PLCs are intended-for and therefore tolerant-of more severe conditions (such as dust, moisture, heat, cold), while offering extensive input/output
FUJIAN Xiamen ZheXun Electric Automation Co., Ltd. [2020-04-15 16:09:57 ]
