help,please

Hello,
could you help me in a ladder logixpro program, please?http://www.plctalk.net/qanda/images/smilies/pray.gif

In Batch simulation
I want to make a program that:
If I press start button pump3 opens and start draining the water then pump1 fill the tank then, mixer and heater work then, pump3 opens again draining water then, pump1 opens filling tank with water then mixer and heater work and so on

The standard is to post what you have done so far and not where you have problems.

thank you for your reply, bernie_carlton
I`m so sorry
I mistake , I mean pump2 opens in next time not pump1
pump3-pump1 then, pump3-pump2

I wasn't clear in my reply.

Provide a complete list of inputs and outputs noting the address of each within the simulator.

Provide the complete sequence, one step at a time. Place each step on a separate line.

State what condition ends each step - the passing of a certain amount of time, the actuation of an input for example.

Post the ladder logic you have developed so far.

bernie_carlton said:

I wasn't clear in my reply.

Provide a complete list of inputs and outputs noting the address of each within the simulator.

Provide the complete sequence, one step at a time. Place each step on a separate line.

State what condition ends each step - the passing of a certain amount of time, the actuation of an input for example.

Post the ladder logic you have developed so far.

Click to expand...

This is the program , I want to modify in it for making pump2 works in next time after pump3 draining tank ,
In other word, pump1 and pump2 exchanging with each other

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and if I press" stop" button while tank is being filled and then pressing "start" button , it will be draing
how can i solve this problem ?

Do you mean that Pump 1 and Pump 2 alternate duty?

At your rung 3, I would have an intermediate flag that runs the "Duty" pump.

Then add code so that Pump 1 or Pump 2 is selected as duty when required. At the simplest level, you could change which pump is duty whenever a pump stops. For example, use a ONS instruction to latch Pump1 as Duty whenever Pump 2 stops, and vice versa. This way, the pumps will always operate alternately.

Ian S said:

Do you mean that Pump 1 and Pump 2 alternate duty?

At your rung 3, I would have an intermediate flag that runs the "Duty" pump.

Then add code so that Pump 1 or Pump 2 is selected as duty when required. At the simplest level, you could change which pump is duty whenever a pump stops. For example, use a ONS instruction to latch Pump1 as Duty whenever Pump 2 stops, and vice versa. This way, the pumps will always operate alternately.

Click to expand...

I`m a beginner in plc ladder programs and I was not completely understand you
could you suggest a code for me?

pump-1/2/3 overload signal put before output pump

temperature ok-> latch the signal to permit pump-3 run.

if pump-1 overload skip to pump 2

if pump-2 overload skip to pump-1

I mean pump2 opens in next time not pump1.
pump3-pump1 then, pump3-pump2.

and if I press" stop" button while tank is being filled and then pressing "start" button , it will be draining. How can i solve this problem ?

Click to expand...

1. First, fix the errors in your program. The Thermostat is a heat-control device. It is not designed to control pumps or mixers. The thermostat will go On and Off when the temperature of the fluid in the tank changes. This has no relation to the tank level or the running times of the Pumps and Mixer. Use a timer to run the mixer for the required 8 seconds as specified in the LogixPro Batch Mix Student Problem. Use a Retentive-type timer (RTO) so that you can stop and re-start the system at any time as shown in the attached picture.

2. To alternate the Pump 1-Pump 2, you need to use "alternator" or "flip-flop" logic. Search this site for many ways to write alternator logic to do this task. I have posted a LogixPro file with 13 different methods to use for alternator logic.