Hi to all a happy new year

I am looking to change an analogue output 0-10v or 4-20mA using the analogue input to slowly increase the output, for example if i have set a temperature to be achieved i want to open a valve 0-10v control slowly based on how long it takes for the system to see the temperature change, this could take 60 seconds, then if the temperature is still not at the setpoint for the analogue input then it will increase the 0-10v again and so on and so on untill it reaches the temperature.

Within this i would like to also incorporate an closed contact that should this contact open then the 0-10v output slowly closes again..

I tried using analogue ramp but it just goes up and down depending on time but i cant change the value of time to increase the delay of it increasing the output. I tried an async timer but it resets the output to zero

Hello Buttsy26,

Have you ever tried using a clocked timer and setting the clock depending on the target/actual value ?

Or try it with the PI controller first.

Greetings Ella_68

(translated with google)

So what i did use was a async timer in the circuit i can make it count up no problem and back down but i would prefer it to be not so fast and as i want to control the time it takes to increase the 0-10v this doesn't work. I have just looked at the Pi system and i hadn't realised that the setting can be put to a different or customer value. This could be handy 

If you have an example of the clocked timer i would like a look

regards

Hello Buttsy26

Buttsy26

So what i did use was a async timer in the circuit i can make it count up no problem and back down but i would prefer it to be not so fast and as i want to control the time it takes to increase the 0-10v this doesn't work.

Somehow I can't quite follow your explanation. If you specify a temperature (setpoint), the control system determines the delay in the temperature. It usually doesn't matter how fast the valve moves. The actual temperature of objects or rooms is much more important.

But if it's just about extending the analog value change for the output, then take a look at the picture

or download the file.

Regards Ella_68

So let me explain a bit better..

If i have a heating area that is 100m away frrom the room i want to heat, opening the valve fully will mean the heat does get to the room but may overheat then have to cut back as its too warm

However if i know that the heat takes about 4 mins to get tot he room and the thermostat to see it i can gradually open the valve each 4 minutes by 1% or 5% each time but the increase will be gradual and so will the heat and with all being equal at some point in about 16 minutes i may be closer to the required value, I would call it process time..

No risk of over shoot and excessive cut back as its to warm, but a gradual increase in heat .

Thanks for your drawing i will have a look much more complicated than i thought 

Hello Buttsy25,

You won't be able to solve the problem this way.

If the valve is at the beginning of the pipe, as you say, the heat alone takes four minutes to reach the room. Added to this is the inertia of the room until the thermostat reacts. The reverse is also true. In the worst case, the control starts to oscillate. If you then also program a delay, this problem gets worse. In your view, lowering the setpoint would first direct the heat from the 100m pipe into the room. Added to this would be the programmed delay in the valve control. The room would continue to be heated until then.

The only thing that could be implemented is a control valve directly on the radiator in the corresponding room.

Regards Ella_68