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 ]
In ladder diagram, the contact symbols represent the state of bits in processor memory, which corresponds to the state of physical inputs to the system. If a discrete input is energized, the memory bit is a 1, and a \"normally open\" contact controlled by that bit will pass a log
FUJIAN Xiamen ZheXun Electric Automation Co., Ltd. [2020-04-15 16:09:14 ]
This is a programming example in ladder diagram As an example, say a facility needs to store water in a tank. The water is drawn from the tank by another system, as needed, and our example system must manage the water level in the tank by controlling the valve that refills the ta
FUJIAN Xiamen ZheXun Electric Automation Co., Ltd. [2020-04-15 16:08:25 ]
There are two types of mechanical design for PLC systems. A single box , or a brick is a small programmable controller that fits all units and interfaces into one compact casing, although, typically, additional expansion modules for inputs and outputs are available. Second design
FUJIAN Xiamen ZheXun Electric Automation Co., Ltd. [2020-04-15 16:07:17 ]
n a parallel development Odo Josef Struger
FUJIAN Xiamen ZheXun Electric Automation Co., Ltd. [2020-04-15 16:06:20 ]
he PLC was developed with several advantages over earlier designs. It tolerated the industrial environment better than computers and was more reliable, compact and required less maintenance than relay systems. It was easily extensible with additional I/O modules, while relay syst
FUJIAN Xiamen ZheXun Electric Automation Co., Ltd. [2020-04-15 16:05:22 ]
PLC originated in the late 1960s in the automotive industry in the USA and were designed to replace relay logic systems. [1] Before, control logic for manufacturing was mainly composed of relays The hard-wired nature made it difficult for design engineers to alter the process. Ch
FUJIAN Xiamen ZheXun Electric Automation Co., Ltd. [2020-04-15 16:04:05 ]
They can be designed for many arrangements of digital and analog I/O, extended temperature ranges, immunity to electrical noise PLCs were first developed in the automobile manufacturing industry to provide flexible, rugged and easily programmable controllers to replace hard-wired
FUJIAN Xiamen ZheXun Electric Automation Co., Ltd. [2020-04-15 16:02:52 ]
