Requesting some help with analog scaling on a wind anemometer.  

Here is the link to what I am working with:https://www.adafruit.com/product/1733

Feeding anemometer with same 12 VDC as LOGO!

Output Voltage range of anemometer:

0.4V = 0 m/s wind speed

2.0V = 32.4m/s wind speed

LOGO! module is 8.FS4_2  (12/24RCE)

Would love if it scaled to MPH since I am in Washington State and we have not adopted the metric standard ‘yet’ .  I calculated 32.4 m/s to 72 MPH.  Does not need to be exact.

Application is for the awning on my RV.  If the wind blows – say over 15 MPH (adjustable) - I want my LOGO! program to close my awning so it does not damage itself or my RV. 

I am playing around with some other fun things to control on the RV but got stuck with the scaling of this and thought I would reach out to some experts for the analog scaling help.

Thanks in advance!

Cheers,

Darren 

A tremendous thank you ixo65! 

I have studied your reply and example in tremendous detail.  Your knowledge of this astounds me and I have learned quite a bit.

You make an excellent point regarding the lower fifth of the measuring range.  I was using the measuring range totally wrong in my configuring.  Your lesson will stay with me.  Makes perfect sense now!  Better to input the full 0-10 to maximize the 0-1000 steps in LOGO! 

I was able to kind’a follow the 160 of the 1,000-unit resolution but I am not sure how to arrive at that on my own.  Can you enlighten me on your thinking there?  I spend several minutes trying to get my head wrapped around that part.  Do you take the lower fifth and divide by the max sensor input???  None of my numbers were working out the same as yours – not for lack of trying though.

In your example – for any given analog input - If the input were a ‘true’ 0-10 than would it take less blocks?  That is to say if the input were using the full 1,000 steps, instead of what my input is providing.  To be honest I would have never come up with what you did.  I need to learn how to see this the way you do.  Can I buy you a beer sometime and sit at your feet to learn more about the analog parts of this?   How to you ‘see’ all the math to know what to do?  Any tips/tricks or resources you can point me to?  I genuinely want to learn this stuff.  

I got this anemometer to play with but am not committed to it.  I realized it is not even weatherproof so it is kind of a toy!  I can get one that counts pulses and it would be a whole lot easier eh’.

I have read a lot of your other posts helping folks out on with their questions – including most of what you have replied to regarding analog.  You are a tremendous resource on this forum!!!

Cheers,

Darren

I am totally tracking with you.  Excellent instruction.  You make it very simple to visualize.  

At first, I was not sure how you ‘calculated’ 0.4 to 2.0V into 40 to 200 but then I saw how it ‘fits’ within the 0-1000 units.  So clear now!  No calculation necessary – it is just where it goes withing the LOGO! internal units.

I lost the trail when you multiplied 32.4 m/s * 3600 but when I looked closer, I saw the conversion from m/s to m/h and there are 3600 seconds in an hour.  Very slick calculation but I didn’t catch it at first – not sure I would have thought to do that calculation to scale the input value.

Thanks for taking the time to work with me on this.  I have also been working through the examples in the LOGO! 8 manual pages 140+ (Calculating the gain and offset of analog values), and also pages 198+ (Analog comparator).  However, I still do not think I would have come up with what you did on the example!   I am still picking it apart and not sure why/how/what is going on there.  If you ever get some free time I would love if you could add more comments on how all that works.

Thanks for the links for more info.  I have already devoured most of that before I reached out for help on the forum.  Believe it or not I started playing with the LOGO! back around ’94 when they first came over to the states!  I think it was like 8 SF.  I still have a few of the LOGO! Longs with the ASi from back then when I put in some ASi networks.  Worked with the Siemens Greenhouse Automation Group (SIGA) out of Dusseldorf for a while and then for Siemens as a Sr. Systems engineer out of Dallas for several years but lived with the S7-300 -400H  world on airport baggage systems.  I like the LOGO! better but got to get my head around this analog stuff!  

Cheers,

Darren

You have been amazing to help me with this!!!    Thanks for the comments on the example.  This has been a tremendous teaching exercise.

I am almost ready for my test…  

I have been dissecting and playing in the simulator.

Some Questions for clarity:

B001, why a -40 offset?  Where does that number come from?   I would think it would be 40 (not minus 40).  Is this not where the usable units ‘starts’ based on previous discussion?

When I simulate AI value from 0 -> 39 the MPH = 0

When I simulate AI value to 40 the MPH jumps to = 18.12

Why the jump?  What happened to the MPH between 1 & 17.66?

B002 & B003 – is this to corral the 160 usable units (out of 1000) based on the sensor input?  So, B002 says cut out anything the sensor is feeding below ‘0’ and block B003 says lock the max usable units to 160?  Do I understand this correctly?  If so, I think I understand the how and why of that step.

B003 why not set max ‘off’ threshold to 2000?

I think I can easily follow the rest of the example but will keep studying.

Thanks again for all your help!!!  

One thing this exercise has taught me is that I do not ‘see’ math the way others do.  You are a mathematical super-star!!!  

Some folks can look at a room and know what element (color, furniture, art) to add to make it pop, others can do the same when cooking by adding certain ingredients.  Your mathematical insight is both beautiful and delicious.  I sit in awe as I savor every bite.

Perhaps LOGO! kind of forces one to rethink how to do things, to get out of the box on how to achieve the desired logical output.  They give up and use a full PLC to do the math.  Those that say the LOGO! is limited are not able to see another way to do things and are missing out on what makes LOGO! so amazing.

Thank you for helping me see math from a LOGO! perspective.  I am better because of the time you have invested in my project.  Thank you, Thank you!

Now, what is for dessert?  LOL