analog input in ladder logic

Ali Sayghe

Member
Join Date
Sep 2012
Location
Tempe
Posts
14
Hi all
I am trying write a program that has analog input from a pressure sensor in a thank that read the pressure sensor for low level and high level when the pump start filling up the tank the motor for gate valve is closed when the water reach the high level the motor for the gate valve will open so the input and the output is:
input I:0/1 from limit switch 1 to turn off the motor when its opening the valve
input I:0/2 from limit switch 2 to turn off the motor when its closing the valve
input I:2/1 analog input from pressure sensor
turn output O/0 when the signal from pressure sensor is low (111)
turn output O/1 when the signal from presser sensor is high (25000)
I have a 1769-IF8 Analog Input Card in a Micrologix 1500 system.
 
...Input I:2/1 [is] the analog input from pressure sensor.
Beacause you are using a 1769-IF8 analog module, I think this analog input should be at address I:2.1 or I:2.0. In other words, it must be a word address instead of a bit address.

I am trying to write a program...
If you would print your program to a PDF file, or ZIP it to a compresed file, and post it here, I am sure someone can help with your problem.

Your action elements are simple and only two:
"CLOSE VALVE MOTOR" and "OPEN VALVE MOTOR". Put two rungs in your program for those Outputs, and you will have a place to start.

Remember, the Inputs do not control the valve, but instead your PLC outputs control the motor that controls the valve.
 
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Beacause you are using a 1769-IF8 analog module, I think this analog input should be at address I:2.1 or I:2.0. In other words, it must be a word address instead of a bit address.

If you would print your program to a PDF file, or ZIP it to a compresed file, and post it here, I am sure someone can help with your problem.

Your action elements are simple and only two:
"CLOSE VALVE MOTOR" and "OPEN VALVE MOTOR". Put two rungs in your program for those Outputs, and you will have a place to start.

Remember, the Inputs do not control the valve, but instead your PLC outputs control the motor that controls the valve.
yes you right i am controlling the valve through the dc motor but my problem is i don't know how can i use less than and more than function to turn the motor whether closing if the level is low or opening if the level is high according to the pressure of the tank the value that indicate low level is 500 and the valve indicate high level 20000 am using the raw/proportional unit for the analog input card. I am using SCP for to scale the input

untitled.jpg
 
..my problem is i don't know how can i use less than and more than function to turn the motor whether closing if the level is low or opening if the level is high according to the pressure of the tank..

The Logic in the Attached Image shows how to do the above with the I/O addresses provided by you in Post #1 and #4.

However, note that if your motor is very slow and the rate of filling is lesser than the rate of emptying through a partially opened valve then you will need to latch the "Open valve" output till it reaches the limit switch because the level may drop before the valve position reaches the limit switch and turn the motor off.

Inversely if your motor is very slow and the rate of filling is greater than the rate of emptying through a partially closed valve then you will need to latch the "Close valve" output till it reaches the limit switch because the level may increase before the valve position reaches the limit switch and turn the motor off.

Valve Motor.JPG
 
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just a note
is the analogue 0~10V or 4~20 mA
because the min max scaling is different for the two
 
The Logic in the Attached Image shows how to do the above with the I/O addresses provided by you in Post #1 and #4.

However, note that if your motor is very slow and the rate of filling is lesser than the rate of emptying through a partially opened valve then you will need to latch the "Open valve" output till it reaches the limit switch because the level may drop before the valve position reaches the limit switch and turn the motor off.

Inversely if your motor is very slow and the rate of filling is greater than the rate of emptying through a partially closed valve then you will need to latch the "Close valve" output till it reaches the limit switch because the level may increase before the valve position reaches the limit switch and turn the motor off.

Thank you very much its really works and i attached the final program

yuy.JPG
 
hello,i am just beginners i am doin a project using plc ...my project is customer receive water from water tanker as per his daily rquirement up to 30 days....after 30 days he need pay amout of that..

how to process this through plc analog process..each day calculation of water amount
 
Simply start with the maths.
Then look at your sensing device/s
Analogue maybe.
Flow or height or weight.
Digital maybe.
Flow meter with pulse output.
how accurate do you need this.
Litres, mega litres or milli litres.
How fast do yo need the delivery rate.

Then finally
What Model / brand PLC are you going to use.
 
sir my plc is micrologix 500. can u plz elaborate with programmable..

what is math logic..
its beginners thats why i am asking details..
plz share with program and algorithims

thanks
iant
 
There are many ways.
But I need to know what equipment you are going to use.
Otherwise I could be writing info for the next 10 years
 
attachment.php


20170104_171946.jpg
 

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