Control ladder diagram of advance and retreat mechanism

PLC control ladder diagram design for bridge crane inspection Ladder hidden programming design of advance and retreat mechanism
There are two types of operation: manual operation and automatic operation. The automatic operation process is as follows:
    1) When the PLC is turned on, an initialization pulse is generated through the internal relay M71, so that Each counter (C460-C463) is reset.
    2) When the automatic operation switch Sl is turned on, the normally open contact of
, the timer T450 generates a pulse every 5s,
the pulse holding time is one scan cycle, and provides the scan signal for the counter.
    3) When 0160 counts to 6, the normally closed contact of C460 is disconnected, causing the Y431 coil to cut off power, and the forward and backward mechanism stops moving forward.
    4) After another 45 seconds, the C461 counter counts to 15, the normally open contact of 0461 is closed, the Y432 coil is connected, and the crane begins to retreat;
after 30 seconds of operation, the C462 counter reaches 21, the normally open contact of C462 is disconnected, and the coil of Y432 Disconnect to stop the retreat.
    5) After resting for 45 seconds, C463 counts to 30, and the normally open contact of C463 closes, which resets all counters and starts counting again, entering
the second cycle.
    (4) Conclusion This paper uses PLC to control the operation of the bridge-type overweight machine, so that on-site inspection can be completed efficiently, which can
fully reflect the powerful functions, high reliability, simple programming and easy use of PLC. , small size and other advantages. The use of PLC can also
solve many troubles in operation under traditional control methods, including problems such as closing the opening and closing motor and the lifting motor to synchronize the lifting pheasant when the grab is just loaded
. At the same time, it can also reduce the labor intensity of workers and improve the working performance of the crane.