Hi.  I have not yet used the LOGO PLC but am trying to find out if it would be suitable for the following application before buying the relevant hardware.  I want to be able to create a voltage output in the range 0-10V that varies in a step sequence with time, over a period of around 24 to 48 hours.  The step intervals will be typically 1 hour (or multiples of 1 hour) and can all be the same duration to keep things simple.  I will need between 6 and 10 different voltage levels.  So for example I would want the output to start a zero volts, then after say 4 hours change to voltage level 2, then after another 4 hours change to voltage level 3, and so on until the full time duration has been reached. At this point the voltage output should return to zero.  I anticipate I will need a basic controller plus an analogue output extension module to achieve this. 

I have had a search through previous posts but cannot find any examples where analogue output profiles are being driven by clocks/counters in this way.  There also appears to be a limitation of only 4 fixed output values being allowed in an analogue mux.  Is there a way of overcoming this to provide the 6 to 10 output voltage levels that I am looking for?

Please could you confirm that the LOGO PLC and analogue output module would be capable of doing this, and if possible provide any examples of how it would be implemented within Soft Comfort?

Any help appreciated

Thanks

Thank you ixo65 for your fast response.  I'll get some hardware ordered.  In the meantime I have downloaded the demo version of Soft Comfort and will work through a few tutorials on how to use it. Do you know where I might find a .lsc example of a cascaded mux please?

I was wondering if i could generate the timing sequence using a clock-driven shift register or BCD counter to generate the selection lines required by the mux to select the different output levels.  I wonder if you are able to recommend the best approach, and again if you know of any examples I could start from?

Many thanks

That's great - thank you very much.  I have now ordered the LOGO kit and will have a look at your examples when i have learnt the basics!  I will let you know how i get on.

Cheers

ixo65 - I have now had chance to grasp a rudimentary understanding of LOGO soft and Soft Comfort and both your solutions look ideal for what I need.  The shift register solution is easier for me to understand at the moment as I have not looked at the complexity of the math functions yet!

I will need to make a few tweaks/additions but you have done the hard work for me - thank you.

I note you have used a shift register that is only supported in LOGO! 8.FS4 and later versions.  What is FS4 and how can I tell if my 12/24RCE controller (when it arrives) is compatible?

I don't think the earlier shift registers had a reset function which is needed for this application?

Thanks again