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PLC Programming Methods and Applications P2

Ladder Diagram Fundamentals 1-5. Machine Control Terminology There are some words that are used in machine control systems that have special meanings. For safety purposes, the use of these words is explicit and can have no other meaning. They are generally used when naming control circuits, labeling switch positions on control panels, and describing modes of operation of the machine. A list of some of the more important of these terms appears below. ON This is a machine state in which power is applied to the machine and to the machine control circuits. The machine is ready to RUN. This is. | Chapter 1 - Ladder Diagram Fundamentals Figure 1-35 - 2-Handed Anti-Tie Down Anti-Repeat SingleCycle Circuit 1-28 Chapter 1 - Ladder Diagram Fundamentals 1-5. Machine Control Terminology There are some words that are used in machine control systems that have special meanings. For safety purposes the use of these words is explicit and can have no other meaning. They are generally used when naming control circuits labeling switch positions on control panels and describing modes of operation of the machine. A list of some of the more important of these terms appears below. ON This is a machine state in which power is applied to the machine and to the machine control circuits. The machine is ready to RUN. This is also sometimes call the STANDBY state. OFF Electrically the opposite of ON. Power is removed from the machine and the machine control circuits. In this condition pressing any switches on the control panel should have no effect. RUN A state in which the machine is cycling or performing the task for which it is designed. This state can only be started by pressing RUN switches. Don t confuse this state with the ON state. It is possible for a machine to be ON but not RUNNING. STOP The state in which the machine is ON but not RUNNING. If the machine is RUNNING pressing the STOP switch will cause RUNNING to cease. JOG A condition in which the machine can be nudged a small amount to allow for the accurate positioning of raw material while the operator is holding the material. The machine controls must be designed so that the machine cannot automatically go from the JOG condition to the RUN condition while the operator is holding the raw material. INCH Same as JOG. CYCLE A mode of operation in which the machine RUNs for one complete operation and then automatically STOPs. Holding down the CYCLE button will not cause the machine to RUN more than one cycle. In order to have the machine execute another CYCLE the CYCLE button must be released and pressed again. This mode