Bridge crane control PLC ladder design Detection retract mechanism ladder hide programming manual and automatic operation of two run automatically follows Runtime: 1) When the
PLC work boot, initialization pulse generated by internal relay M71, so each counter (C460-C463) reset. 2) When the automatic operation switch Sl is closed, X400 normally open contact closure, Y431 coil connected machine retreat plum actuator forward, then the contactor is energized, the crane started to move} Also, all timers, counters start work, the timer T450 produces a pulse every 5s, a hold time of a pulse of the scan period, supplying a scanning signal to the counter. 3) When the 0160 count to 1-6, C460 normally closed contacts open, so Y431 coil power, retract mechanism stops. 4) a few 45s, C461 counter to 15,0461 normally open contact closure, Y432 coil connected, cranes began to recede; to work after 30s, C462 counter to 21, C462 normally open contacts open, Y432 coil oFF, the back stop. 5) After a break 45s, C463 counts to 30, C463 normally open contact closure, so that all the counter is reset, and counting resumes fork into the second cycle. (4) Conclusion inverted by using PLC to control the operation of the bridge overweight machine to detect in the field can be efficiently completed, can fully reflect the PLC has the function, high reliability, programming is simple, easy to use, small size and other advantages. Using PLC can also solve a lot of trouble under the traditional control manipulated, including the opening and closing of the motor and the motor when lifting the grab just closed loading lift pheasant in the same step and other issues. At the same time, it can also reduce labor intensity, improve work performance crane.