logo question

walters

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Join Date
Feb 2005
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reusel
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my boss wants me to make a program for pulse counting on a siemens logo PLC. im a trainee at ths company and i never worked with a logo before. i looked around in help and google but my guess is that i think to hard for this
plc

the job is this:

with a thumbeel-switch(hope i translated that wright) connected to the digital inputs of the logo and a pulsing fotocel i must make an ouput high for example: when i say with the switch that the output must get high on the positive flank of the third pulse from the fotocel the output must be high as long as that third pulse is high no more pulse no output signal.
i think that i must make this with a shiftregister but i have no idea how i must do this
please help me

regards walters
 
hello,

you did not provide suffeint information to give us a better idea, LOGO is the easiest ladder programing language out there, it does not solve complex PLC programing tasks, just basic bool ladder, with latching realys and timers. what is the task to be exact. exaplin more in detail. and i will try to help
 
I think I understand what you are saying, let me rephrase it and see if it sounds right.

You said you were going to use a thumbwheel but it sounds like all you need is to select between the 4 inputs. If you select input 3 then when you get the 3rd (third) pulse from the photoeye you make an output go high (ON) and stay high (ON) as long as pulse is high.

I think alot would depend on the frequency of the pulses but if the pulses are slow, less than scan time, then I dont see why you couldnt do this.

If you just want to use the 4 inputs to choose the pulse to use I doubt a thumbwheel is needed, just use a selector switch.

Provide more details so a better answer can be provided.
 
we are gonna use a siemens logo with 8 DI and 4 DO the thumbwheel will be connected to the first 4 inputs of the plc and the photocel to another input. depending on the number selcted with the thumbwheel the pulses must be counted untill that number is arrived. when that number is arrived the output gets high on the positive edge of the pulse and it gets low on the negative edge of that same pulse. what i want to know is must i do this with a shift register is is a simple counter enough to do the job. and what block do i need for that its what i said i dont know the program or anything about logo :cry:
92042306.jpg


 

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