Small Lua coding examples required

Hi all, I have a test bench rigged up with a Shac and some dimmers and relays. I was wondering if anyone had any small Lua code examples to get me familiar with using the coding side of the shac. Any help would be much appreciated.

 

what sort of function do you want to achieve?

 

Hi Pie Boy,

Ultimately I would like to create a function for a toilet extraction fan and light on the same input. For example if light is on longer then 1minute turn fan on. When light is off run fan for a further minute.

There is an example under a Thread called “Fan Timer” that seems to fit my situation but could not get that to work.

 

Timers and delays are a complex thing in the shac unfortunately, there may be a better way than this but here goes, the other thing you could try is the PulseCBusLevel() but i couldn't get it to work like a delay timer as below...

set a resident script to run with 1 second delay with this code

Code:

local timer_t  = storage.get('obj_timers')
if timer_t  then
  
  for index, val in pairs(timer_t) do
    s = string.split(index, '/')
    nettag, apptag, grouptag = CBusLookupAddresses(tonumber(s[1]), tonumber(s[2]), tonumber(s[3]))
    if index then
         if (os.time() - val[1]) > val[2] then
          SetCBusLevel(s[1], s[2], s[3], val[3], val[4])
          log('Timer Switched object '..s[1]..'/'..s[2]..'/'..s[3].. ', '..grouptag..' to level ' ..val[3] .. ' at '.. os.date("%H:%M:%S"))
        timer_t[index] = nil
         end
        else
         index = nil
        end
    end
end
 
storage.set('obj_timers', timer_t)

then in common functions put this code

Code:

function timer_Start(obj, delay, level_after_delay, rate_after_delay)
  local timer_t = storage.get('obj_timers')
  local s = string.split(obj, '/')
  local index = s[1]..'/'..s[2]..'/'..s[3]
 
    if s[4] ~= '-1' then
  SetCBusLevel(s[1], s[2], s[3], s[4], s[5])
  nettag, apptag, grouptag = CBusLookupAddresses(tonumber(s[1]), tonumber(s[2]), tonumber(s[3]))
  log('Timer Switched object '..index.. ', '..grouptag..' to level ' .. s[4] .. ' at '.. os.date("%H:%M:%S"))
    end
 
  if timer_t then
   else
      timer_t = {}
   end
     timer_t[index] = {os.time(),delay,level_after_delay,rate_after_delay} 
  storage.set('obj_timers',timer_t)
end


function Timer_Stop(obj)
 local timer_t = storage.get('obj_timers')
 
   for obj, val in pairs(timer_t) do
       s = string.split(obj, '/')
       if obj then
      log('Timer stopped for object '.. s[1]..'/'..s[2]..'/'..s[3]..' at '.. os.date("%H:%M:%S"))
            timer_t[obj] = nil
        end
    end
  storage.set('obj_timers',timer_t)
 
end

To use the timer functions use event script using the ga for the light as the trigger to start the event script
parameters for timer is
timer_start(network/app/group/level/ramp rate/delay time in sec/level after delay/ramp rate after delay)

Code:

--Guest toilet
local level = event.getvalue()
fan_ output_ga = 76

if level == 255 then
  -- delay 60 sec then switch Fan on 
   timer_Start('0/56/fan_ output_ga/0/0' , 60, 255, 0)
end

if level == 0 then
  -- if off button is pressed straight away after on
  Timer_Stop('0/56/fan_ output_ga')
 
 -- switch fan on if off then set timeoutafter 2 min
  if GetLightingLevel(fan_ output_ga)  ==  255 then
    timer_Start('0/56/fan_ output_ga/255/0' , 120, 0, 0)
  end
 
end

 

Thanks a lot for helping out, i just tried inserting the resident script and keep getting the error message "Lua syntax error at line 1: unfinished string near ''obj_timersf timer_t then" is there something i am missing?

 

for some reason the forum is not formatting the code correctly... check your messages,
in some instances it removes ') not sure why as when i go to edit it it comes up as correct, when i save it it removes some char

 

Hi,

You asked me about the code I'm using, referring to the earlier mentioned fan timer.

Start with your two groups, lets call them "UPSTAIRS TOILET LIGHT" and "UPSTAIRS TOILET FAN".

I've added some keywords to each of these called "upstairs_toilet_light" and "upstairs_toilet_fan" respectively.

I'm doing somethine a little different which is calling the database directly for a couple of functions which weren't handled via inbuilt functions.

Create a user library, I generally create and name them based on functionality. Call it userfunctions or something if you prefer.

Add the following function to the new library.

Code:

function db_GetObjectById(id)

    -- Return a table of object parameters based on the id
    local query = string.format('SELECT * FROM objects WHERE id = "%u"', id)
    liste = db:getall(query)

    if (table.maxn(liste) ~= 0) then
        return liste
    else
        return false
    end
    
end

Attach an event script to the light group ad add the following code. The below script relies on the above mentioned tags being the first tags (multiple tage are allowed)

Code:

value = event.getvalue()

-- DB Call to return object based on the raw id number
local objLight = db_GetObjectById(event.dstraw)

if (objLight == false) then
    log(string.format('FAN TIMER: Object \'%s\' was not found', event.dstraw))
else

    -- Pull out tagcache table
    local tagcache = split(objLight[1].tagcache, ',')
    local light_keyword = tagcache[1]

    -- Substitute the tags to get the fan keyword
    fan_keyword = string.gsub(light_keyword, "_light", "_fan")

    -- Get CBUS Level
    objFan = GetCBusByKW(fan_keyword, 'or')

    key = light_keyword

    -- If the light is switched on AND the fan is currently off, add to the storage variable
    if (value == 255 and objFan[1].value == 0) then
        log(string.format('FAN CONTROL: Light \'%s\' ON', light_keyword))
        storage.set(key, os.time())
    
    elseif (value == 0) then
        log(string.format('FAN CONTROL: Light \'%s\' OFF', light_keyword))

    end

end

Create a 1 second resident script and call it "Fan Control Timings" or something. Now put the light and fan keywords into the timer_mappings object in the below code. You can repeat for as many fans as you want to control.

So what happens is that once the light is turned on, it will run the below script once a second and check if on_delay has decremented to zero. If so and the light is still on then turn on the fan. Once the light has turned off the fan will continue to run for off_delay seconds.

Code:

-- Script runs each second (or whatever you want) and checks for stored values based on the timer_mappings table
-- Add an entry for each light and fan combination needing to be controlled


if not timer_mappings then                                                        -- set up light to fan mappings table
    timer_mappings = {
        {input = 'downstairs_bath_light', output = 'downstairs_bath_fan', status='idle', on_delay=120, off_delay=180},
        {input = 'upstairs_toilet_light', output = 'upstairs_toilet_fan', status='idle', on_delay=120, off_delay=180},
        {input = 'test_light', output = 'test_fan', status='idle', on_delay=5, off_delay=10}
    }
end


for _, timer in ipairs(timer_mappings) do                                        -- Loop through each line in the table

    
    keyval = storage.get(timer.input, 0)                                        -- Get the stored value matching the input if it exists
    now = os.time()

    if (keyval > 0) then                                                        -- If the storage key exists (ie, greater than a value of zero)

        delta = now - keyval                                                    -- Calculate the difference between now and the stored value
        
        objLight = GetCBusByKW(timer.input, 'or')                                    -- Get the lighting object and extract the current state into light_state
        light_state = objLight[1].value

        objFan = GetCBusByKW(timer.input, 'or')
        local send_to_log = objFan[1].log                                        -- Get the groups 'log' flag

        
        if (delta >= timer.on_delay and timer.status == 'idle') then                -- Turn on the fan if required
            if(light_state == 255) then                                            -- Check if the light is still on and if so, turn ON the fan
                SetCBusByKW({timer.output}, 'or', {target = 255, ramprate = 0})    -- Set the fan ON
                timer.status = 'fan_on'                                        -- Set OFF delay time
                storage.set(timer.input, os.time())                                -- Save current time and light keyword to storage
                
                if(send_to_log) then
                    log(string.format('FAN CONTROL: Turning Fan \'%s\' ON', timer.output))
                end
                
            else
                -- Set op back to idle if light if now OFF
                timer.op = 'idle'
                storage.delete(timer.input)
                
            end
            
        elseif (timer.status == 'fan_on' and light_state == 255) then                -- If light and fan are both ON
            storage.set(timer.input, os.time())                                    -- Keep resetting the current time for when light goes OFF
            
        elseif (delta >= timer.off_delay and timer.status == 'fan_on' and light_state == 0) then
            SetCBusByKW({timer.output}, 'or', {target = 0, ramprate = 0})        -- Light off, timer expired, turn fan OFF
            storage.delete(timer.input)                                            -- Delete the storage variable
            timer.status = 'idle'                                                        -- Set timer op back to nothing
            
            if(send_to_log) then
                log(string.format('FAN CONTROL: Turning Fan \'%s\' OFF', timer.output))
            end
        else
        
        end
    
    elseif (keyval == 0 and timer.status ~= 'idle') then                                -- In case something messes up and gets out of sync
        timer.op = 'idle'
    else
    end
end