ACMCspark

PLC Input Output sequencing

7 posts in this topic

Hi all , new on site and looking for some help please. Need simple solution to the following example. Imagine a clock face. At every 45 degrees , I need an input and an output from the same input some milliseconds later. Before I get to 90 degrees , input 1 is now off awaiting input 2 at 90 degrees and so on. For my 360 degrees , this would require 8 inputs and outputs with only one input / output active at any one time with the program repeating the sequence continuously when back to zero degrees. Info please on suitable small inexpensive PLC and any suitable position feedback device , thanks , Al..//

Edited by ACMCspark

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you did not provide nearly enough of info for a reasonable answer.

what is this 'something' that is turning around? are you driving it or monitoring it or both? how fast? what radius (wrist watch face or face of large Abraj_Al_Bait)?

what is this 'input' and 'output' you need? since it is in milliseconds response, small and cheap may not do it. or you may want to consider FPGA or microcontroller.

inexpensive in what way? money or time? and which type (development or per finished product)?

what is this 'some delay'? is it fixed or adjustable? what interface?

 

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Ok Panic mode , let me try a little harder....let us say the something is a driven wheel for monitoring only and the diameter is 25cm . The wheel speed is say 10 RPM. I did not realise linear speed was of most importance at this point in my question. On every radial 45 degree increment , the input device , as yet undetermined inputs to the PLC and very soon after outputs to a solenoid or lamp for say 2 seconds.This input and output then resets before the next position at 90 degrees then 135 degrees and so on. I had assumed radial position might be possible using some sort of direct mechanically coupled encoder to input to the PLC rather than a switch or transducer , thanks , Al..//

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there are endless options, i was just trying to narrow it down:

you mentioned ms delays (!) and this sounds time critical and could be pricey using conventional PLCs since cheap ones are not going to be fast enough. on the other hand, if you wish to make own custom solution to market it as a product, you could make them for some $1-2 per unit which is size of a penny.

if the speed is not great and we don't need millisecond or microsecond timing, even mechanical solution could be used (camswitch).

there is tons of encoders and small PLCs of every shape and size to choose from. most small 'brick' PLCs have an encoder input but again - helping with selection requires some input from you.

 

ok, enough of that - reality check:

10RPM  -> one revolution is 6 seconds.

 

if each output is on for 2 seconds and we have to go through 8 of outputs during one revolution and - only one of them can be set at any time, we need 8*2sec=16sec. this is longer than 6sec you required...

 

soooo....care to try harder?:slydog:

 

 

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Great PM , now we are getting closer...so we will use the small brick PLC as you suggest with encoder and forget the millisecond thing...wheel speed is now 15RPM and each output time is now 1.5 seconds....this is all I am trying to achieve...8 inputs and 8 outputs 45 mechanical degrees apart with only one I/O active at any one moment in one rotation cycle. Any small timing adjusments to each output time should be made in the program. As for the camswitch I had kind of disregarded this idea due to mechanical issues , contact bounce etc...thanks.. Al..//

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This all seems un-necessary unless it's just an exercise as dedicated equipment exists that do just this.

Programmable cam switch

 

Steve

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Thanks nehpets , I have just downloaded manual and this looks good , happy days..Al..//

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