basics ladder logic

Posted on Feb 4, 2014

Ladder logic programming method is a method commonly used in electrical simulation schematic control system programming languages evolved. A circuit control system but the basic purpose of the decision in some cases all the load circuit should be opened or closed. So as to understand the ladder line, the flow of the circuit should be remembered that the concept - when the current can flow to a load, it will

basics ladder logic
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be opened, and when the current can not flow to a load, it will be off. The most basic element of the ladder is a " point" (). Point of only two states: open or closed. Open circuit current will not flow through the points, but closed it when the current will flow through to the next element. The simplest point of is the need to external forces (such as a human finger) can change the state of the switch. Limit switch is placed in different positions of mobile machinery and equipment small switch, when the mechanical equipment will be moved to a location corresponding limit switch is set to open or closed state. If the point is connected to the load and the is closed, then the load will be activated. The following simple example illustrates the basic ladder programming in general: Method: As shown above, the left vertical line is the "power" line, the current must flow through the "butt" to start the load "lamp. " (In fact, right where the load should have a vertical line to allow the return of electricity to the power process the negative side, but the reasons were to simplify the circuit diagram omitted). Now, if you are not directly to the power through the "butt" switch and then received a light load "light bulb", but rather the switch "butt" to connect to the PLC`s digital input, and will "light bulb" to connect to the PLC`s switch output, and then into the inside in the PLC ladder program, the effect would be exactly...

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