logo 8 4-20ma pressure sensor and scale to kg

What I am thinking maybe it is not correct or even not necessary in terms of displayed accuracy in kg witch I want to achieve.

So first step first...

I am going to empty and refill tank by weight get all points, see the displayed accuracy and report back for suggestion.

Thanks a lot.

Chris

edit: From what I understand since I don't use the all 400mbar of the sensor if I get a sensor of 250mbar that is more suitable for this tank I could have better resolution and accuracy.

Hi to all.

I guess I will continue to this thread instead of making a new one so all the history can be found easily.

If a moderator suggest to make a new thread, I will do so.

A year ago a very helpful member help me to my task. This year I wan to make my project even better and expand it to an additional smaller tank.

The FB program suggested was very good straight forward out of the box and this was what I used to run. Since my tank is not a uniform shape, this friend divide the calculation to 3 sections. But since the mbar of the sensor was wrong choice for the height of the tank I never run in to section 3 of calculation which I want to remove from calculation and screen.

Next problem was that the accuracy (due to the wrong sensor was something like 40-80 kg playing up and down. So we color our products and not sure if we spend 500kg of color or 460 or 540.

To improve this I install a more suitable sensor (250mbar) to this tank.

Since I have the old sensor (400mbar) as a spare and I have another builted tank smaller dimensions just next to the original tank doing same job ,I install this sensor to the other tank. Will be more accurate to this tank because this tank has almost the half volume.

Another task is that I use due customer requests different materials with different e. Meaning for example 1m3 of material 1 is 1400kg, 1m3 of material 2 is 1500kg etc.

I really don't want to change by plugging the laptop and chance the calculation every time I change material. (may change 2 times a day or even 3) Also the color material change can be done at hours I am not present so I try to find a way to be very easy and straight forward for the operators.

I am thinking  next approach...install some switches with decals on the cabinet so take advantage of some of the digital inputs.

If  I1 and I2 is on then display Analog 1  (250mbar) and big tank measurements  for material 1

If  I1 and I3 is on then display Analog 1  (250mbar) and big tank measurements  for material 2

If  I1 and I4 is on then display Analog 1  (250mbar) and big tank measurements  for material 3

And

If  I1 is off and I2 is on then display Analog 2  (400mbar) and small tank measurements  for material 1

If  I1 is off and I3 is on then display Analog 2  (400mbar) and small tank measurements  for material 2

If  I1 is off and I4 is on then display Analog 2  (400mbar) and small tank measurements  for material 1

I guess that what I need first is the two scales of the two different sensors to be running so I can fill each tank with each material and take points of different ma so I would be able to make the calculations later.

I am not humiliar with this and certainly I can not complete this task by myself.

All help I can get is welcomed

The FB program running at the moment can be found at the previous page as a zip file.

Thanks in advance

Chris

The only program i have found is the proposal of ixo65.

1. Where is the adjusted program for your tank you are using now ?

2. Where is the spreadsheet with enough points for height and volume ?

3. Have you a base program for the next version or think you about some other people will create the complete program ?

4. Have you a drawing of your tank with exact dimensions, not a list of data to create a drawing by other people ?

The background of the drawing is to get a mathematical relation between height and volume. If it is an unshaped tank, a detailed spreadsheet will help. Then upload it as excel file.

There is no problem to switch between 2 sensors and 3 materials, but we need more details. Do you have one Logo plc with 2 tanks or two Logo plc and want to select the appropriate sensor for this Logo ? You know the details, we not.

Regards, Scorp

Hi Scorp,

Thanks for your input.

1.The proposal of ixo65 is what I run in the moment. In this program you will see that he made it like 3 different sections to cope with the unlevel and not exactly perfect rectangular shape of my concrete  tank with cone bottom. As it is, section 1 and section 2 reading are almost perfect. Maybe very small deviation but very close. Due to sensor wrong choice I never get in section 3 because I will never see a level of 3 m as my tank is about 2m height and never full to the lip. So I want the section 3 and total calculation of it to be removed. But it is a FB with weight of calculation that sum up everything and I don't know if I can just delete it without affecting anything else.

2. I have a spreadsheet  with points but was done like this.

From empty tank I get ma of sensor on reading (was not exactly 4ma but something like 4.92ma). Then add 500kg (of material color (heavier than water) and get new ma readings. Then again 500kg so 1000kg total and get ma again. When my tank was completely full I had a reading of almost 12 ma not 20ma or close to this value. (due to sensor being 400mbar)

That small resolution 800 points (for the 16ma range) in addition of using only 8ma range of the total of the sensor caused me an inaccuracy of 40-80kg for each painted product.

That's why I took a new sensor more suitable for the tank.(250mbar)

I guess I have to make same job again by filling the tank with known weight of material and getting ma to make a spreadshit for you. But for doing so I need someone to scale for me the new sensor. Or it will be left unscaled using the same scale of the old different sensor. I am very confused.

3. I have the base program I run. The proposal of ixo65. I was thinking of someone help me to do so. I don't mean, me drinking coffee and someone else doing the hard work for me if you mean this.

If you look my screen you will see 20 or more attempts of modifying ixo65 base program to fit but not good results.  

4. The problem with the tank is that it is not leveled. And that it has a cone bottom. Cone bottom is 1500kg of material. From there and upwards, If you measure  a random level of material to 4 top corners (top lips of tank) you will get 4 different height readings.

I will edit later and will provide almost accurate dimension of the tank but will not help much.

The mathematical relation expressed in the program for section 1 (cone) and section 2 (rest tank) is perfect as it is and don't want to be changed.

Also I use one logo plc with 2 sensor connected to the two analog inputs of the expansion module .going every sensor to its own tank.

I want to switch between sensors (tanks) so operator can see that he is at...(Big tank , material 1, and get weight) or (small tank, material 3 and get weight). It is a special reason I don't want to display volume and want weight to avoid a calculation later on from operators I don't trust to do simple mathematics. 

What I was thinking was to copy paste inside the program a few times (as many as my materials are) the program I run at the moment and change the weight factor to display different kg for each material. Then copy-paste  all of the above for the other tank. Also I have a problem managing the digital inputs to enable which analog input to monitor and how to select the materials afterward. And proper way to re scale the sensor at least the new 250mbar one.

Also my knowledge programming is only FBs not ladder or anything else and simple things like few digital inputs with ands /or and timers enabling digital output (relay). But I am very willing to learn or follow directions.

Also if you look the program I run, some FB are not connected by line but have a green sign like shortcut to avoid many lines. How the f... I can deploy this and see the actual line which is easier way to me to see where everything is connected.

Also some blocks have a very helpful comment from the very helpful member ixo65, some others not and I have no other way to understand how he made things so I probably achieve to duplicate.

Thanks in advance

Chris

p.s. even suggestion or directions to follow or pointed comments on the program I run would be tremendous help for me

Scorp

The only program i have found is the proposal of ixo65.

1. Where is the adjusted program for your tank you are using now ?

2. Where is the spreadsheet with enough points for height and volume ?

3. Have you a base program for the next version or think you about some other people will create the complete program ?

4. Have you a drawing of your tank with exact dimensions, not a list of data to create a drawing by other people ?

The background of the drawing is to get a mathematical relation between height and volume. If it is an unshaped tank, a detailed spreadsheet will help. Then upload it as excel file.

There is no problem to switch between 2 sensors and 3 materials, but we need more details. Do you have one Logo plc with 2 tanks or two Logo plc and want to select the appropriate sensor for this Logo ? You know the details, we not.

Regards, Scorp

I never thought you were lazy because you write a lot in your posts. But this is more work for me, because my native language is german. Sometimes it is better to use fewer words with more details. 

Look to attachment, i have tried to change the program from ixo65 with additional sensor and inputs for selections of sensors and materials. Maybe it will help you to your next step. The multiplexers sensor 1/2 mult/div are for scaling the total value. The Logo only calculates with integer, so scale 1.234 as mult=1234 and div=1000. If have a preset of 1.000, 2.000 and 3.000 for the 3 materials just to show in the simulation, change it as you need.

Use the online help from Logosoft to understand the programming, every block is described.

Regards, Scorp