PID thermostat with LogicMachine

[Domoticatorino]

Hi,
as you know on example section there is script to realise 30 PID Thermostats. As you can see PID is 1 byte but I should manage the histeresy in 1 bit. 2 point valve on/off.

Have you idea to modify the PID script?

Thank you very much.

Claudio

[Erwin van der Zwart]

Hi Claudio,

You can put a event based script on the 1 byte output and write a bit output to another object

Code:

output = event.getvalue()
if output > 0 then
   -- Get value of object to avoid write true on each 1-100 value
   bitvalue = grp.getvalue('yourbitobject')
   if bitvalue == false then
      grp.write('yourbitobject', true)
   end
else
   -- Get value of object to avoid write false on each 0 value
   bitvalue = grp.getvalue('yourbitobject')
   if bitvalue == true then
      grp.write('yourbitobject', false)
   end
end

BR,

Erwin van der Zwart

[buuuudzik]

Maybe the solution is the PWM controller? For example when your value is 50% and time T is e.g. 1hour your valve will be switched on for 30minutes and switched off for 30minutes. It will be better for the relay because you will have less switching.

[admin]

Or you can just modify setoutput function to send boolean true when value >= 10, false otherwise:

Code:

function PID:setoutput()
  local t, value

  self.output = math.max(self.output, self.params.min)
  self.output = math.min(self.output, self.params.max)

  value = math.floor(self.output) >= 10
  t = type(self.params.output)

  if t == 'string' then
    grp.write(self.params.output, value, dt.bool)
  elseif t == 'table' then
    for _, output in ipairs(self.params.output) do
      grp.write(output, value, dt.bool)
    end
  end
end

[Domoticatorino]

Thank you very much for your effort.

[buuuudzik]

How can I use this script for individually controlling a few zones? Could somebody prepare some little example?

[admin]

You can either create a new script for each zone, or several instances per script.

Code:

if not p1 then
  p1 = PID:init({ ... })
end

if not p2 then
  p2 = PID:init({ ... })
end

p1:run()
p2:run()

[leonidas]

How can I stop this thermostat?
http://openrb.com/example-pid-thermostat-with-lm2/

[admin]

You can set manual parameter to a group address. Setting this group to true will disable the PID algorithm.

[Bobby]

I have an on/off output, and this works ok. But is it possible to get the output to work like, with 10% gain, it will have 1 min on, and 9 min off. with 60% gain, 6 min on, and 4 min off?
i hope you understand what im meaning..

---

Today its like attached picture. 
But the water haeating system will then have a warm floor when on, and cold when off. is it possible to have the thermostat work in cycles?

[admin]

Use this script (resident, sleep time = 5 seconds) to convert 0..100% value to slow PWM (proportional on/off). Change input/output objects and period time as needed.

Code:

input = '1/1/1' -- proportional value input (0..100%) object
output = '1/1/2' -- on/off output object
period = 10 * 60 -- 10 minutes in seconds

date = os.date('*t')
seconds = date.hour * 3600 + date.min * 60 + date.sec

curr = seconds % period
perc = math.floor(curr / period * 100)

state = grp.getvalue(input) > perc
grp.checkwrite(output, state)

[Bobby]

Hi again!

then i changed my residential script back to basic, as shown here: http://openrb.com/example-pid-thermostat-with-lm2/
add another residential script, as described above.

I cannot get any output for 1 byte scaled object. it shows 0% even if the setpoint is 5 degrees higher than current value.
if i change the scaled object to 50%, the output will change from '0' to '1'. so the last script should be ok.
please take a look at the attached pictures, and tell me where i went wrong...

[admin]

You need to change the PID user library back to the original version and do full resident script restart via disable/enable, otherwise new library code won't load.

[Bobby]

Yeay. did a backup, rebooted. When started up, 16 of my OV - PID adresses was gone. run the backup, still missing. what happened? is this a fault in LM? all the values was 0%. do they need to be changed for remembering?

---

Actually, several group addresses, who i have changed name on, is missing???

[admin]

Looks like microSD card in your LM became read-only. You need to replace it with a new one an run recovery procedure. See more info here: http://openrb.com/reflash-logicmachine3-...-software/

[Bobby]

Looks like microSD card in your LM became read-only. You need to replace it with a new one an run recovery procedure. See more info here: http://openrb.com/reflash-logicmachine3-...-software/

What is recommended size?

[Daniel]

Looks like microSD card in your LM became read-only. You need to replace it with a new one an run recovery procedure. See more info here: http://openrb.com/reflash-logicmachine3-...-software/

What is recommended size?

It is up to you, we use from 4GB and up.

[Bobby]

Changed the SD card, everything is ok again. thanx!