Fan Logic

Have a cbus network where the 3 speeds of a fan are connected to 3 relay channels.
Is there a fairly easy way to ensure that only one of these is selected at the same time.
Have played around with Lua and not really got it working ok.Have also tried making 3 scenes but still need to ensure only one is selected
Thanks

 

are they all on the same relay? you can do interlock with relay logic

 

Why not get a sweep fan controller? They “just work” and are designed for the task including software based startup power to spin up the fan before settling in to the selected speed. Last I looked they were cheaper than 3 channels on a relay unit.

 

You need to put them on channels 1,2 and 3 of the relay. Then on the Turn ON tab, use the Interlock drop down and set 3. Then only the highest of set channels 1-3 will be on.

But chromus is right. Just go buy a fan controller.

 

Thanks for replies
I have just installed a SHAC at an existing installation where the CTC has failed.
There are 5 fans in total and one 12 channel relay has 4 fans each wired using 3 channels.
I managed to get the old program out of the screen and the fans had logic to enable you to step through the speeds on a DLT.
That logic seems easy but with LUA I am struggling.
Don't think they would want to buy 5 fan controllers and the relay logic would not work the way the relays are wired.
Also from memory that method does interlock the channels but on the SHAC for example it would still show all the channels on if they were selected even though only one would be on.
Thanks again for info and any other suggestions welcomed.

 

If you post the existing logic we can help you convert it to lua.

 

This might get you started, i use this code for something else but i made a few small modifications, it may suit what you need, this code runs in an event script which happens every time the trigger GA group address changes value.

Code:

--EDLT fan controller sets the Triger_Ga to 33%, 67%, 100%, 0% in a circular function (low, med, high, off)

Trigger_Ga = CBusLevelToPct(event.getvalue)

output_speed_1_GA = 1  -- change Ga numbers to match
output_speed_2_GA = 2
output_speed_3_GA = 3

function chk_grps()
speed_1_pct = CBusLevelToPct(GetLightingLevel(output_speed_1_GA))
speed_2_pct =  CBusLevelToPct(GetLightingLevel(output_speed_2_GA))
speed_3_pct =  CBusLevelToPct(GetLightingLevel(output_speed_3_GA))
end

chk_grps()

-- get current speed that is currently on
if speed_1_pct == 100 then
  current_speed = output_speed_1_GA
else if
    speed_2_pct == 100 then
    current_speed = output_speed_2_GA
  else if
      speed_3_pct == 100 then
    current_speed = output_speed_2_GA
    end
  end
end
 
     
if Trigger_Ga ==  33 then --low
  log('Fan Speed Low')
  -- set current running speed off
     SetLightingLevel(current_speed, 0, 0)
  -- get new values as we just switched one off
  chk_grps()
  -- set new speed if the other two GA are off
  if speed_2_pct == 0 and speed_3_pct == 0 then
     SetLightingLevel(output_speed_1_GA, 255 , 0)  -- speed 1
  end
end

if Trigger_Ga ==  67 then -- med
  log('Fan Speed Medium')
  -- set current running speed off
     SetLightingLevel(current_speed, 0, 0)
   -- get new values as we just switched one off
  chk_grps()
  -- set new speed if the other two GA are off
  if speed_1_pct == 0 and speed_3_pct == 0 then
     SetLightingLevel(output_speed_2_GA, 255 , 0)  -- speed 2
  end
end

if Trigger_Ga ==  100 then -- high
  log('Fan Speed High')
  -- set current running speed off
     SetLightingLevel(current_speed, 0, 0)
   -- get new values as we just switched one off
  chk_grps()
  -- set new speed if the other two GA are off
  if speed_1_pct == 0 and speed_2_pct == 0 then
     SetLightingLevel(output_speed_3_GA, 255 , 0)  -- speed 3
  end
end

if Trigger_Ga ==  0 then -- off
  log('Fan Speed Off')
  -- set current running speed off
     SetLightingLevel(current_speed, 0, 0)
end
 

 

oops there is one typo... swap out this part, i missed the output_speed_3_GA for speed_3_pct .

Code:

-- get current speed that is currently on
if speed_1_pct == 100 then
  current_speed = output_speed_1_GA
else if
    speed_2_pct == 100 then
    current_speed = output_speed_2_GA
  else if
      speed_3_pct == 100 then
    current_speed = output_speed_3_GA
    end
  end
end

 

Thanks for info
Away for a few weeks will report back as soon as I get home