The most appropriate command to use in this application is the MELSEC ‘PLS’ (Rising edge
Pulse). It has been adopted here instead of the IEC instruction R_TRIG (Rising edge Trigger)
instruction, which would also be suitable.
The following diagram illustrates the order of sequencing of the carousel control. Note that the
rising edge of the foot switch triggers the motor ON, irrespective of the “In Position” sensor being
ON.
When the table begins rotating, the “In position” sensor turns OFF a little later. The motor contin
-
ues to drive the carousel conveyer until the rising edge of the “In Position” sensor is detected;
this turns the motor OFF. Note that the foot switch continues to be held on.
The Motor can only start rotation when the foot switch is released and subsequently reactivated.
Hence the motor starts again on the rising edge of the Foot Switch being operated.
Timing Diagram of Carousel Control Logic:
Building a Project Application Program
Training Manual GX IEC Developer 4 - 5
Foot Switch
In Position
Motor
Foot switch
Motor
In position
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