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| 9/29/2012 9:14 PM | |
Joined: 1/28/2009 Last visit: 2/21/2023 Posts: 6794 Rating:
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Hello , For reason of using Positive (Negative) edges,please read the following thread: use positive edgeA detailed description of different types of Edge evaluation instructions(in LAD or FBD)are available here: Positive and negative edge instructions 3 different types of edge functions can be categorized for S71200: 1- Edge evaluation with contacts.State of this contact is "True" when a positive(or negative) edge sensed in input signal (signal in upper side of contact) and memory in downside is used to keep last status of input. The status of contact is combined with input signal status and generate the output signal status.As an Example, using these contacts in set and reset input of a flip-flop. IN |-------|P|---- MEMORY 2-Edge evaluation with coils,status change of signal entering the coil is used to create short pulse in OUT signal on the coil.This output signal can be used in the rest of logic (e.g by a contact). OUT -------(P) MEMORY 3-Edge evaluation via Q-boxes.2 Q-box functions (P_TRIG and N_TRIG) are used to check edge change in current flow before the box(CLK input) and short pulse in "Q" output.These boxes also need memory to keep the current status of the input. More information available in the provided link. Best regards Hamid Hosseini |
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