SHAC ramp group begins at level zero

I have a script that is watching for level changes of groups, and is being messed up slightly when CBus groups get ramped on.

It would seem that the first level set during a ramp on is zero, then increasing values are seen after that. My script interprets this as an "off", followed quickly by several "on" triggers as the ramp progresses.

Can anyone confirm that this is actually what LUA code should see during a ramp? It seems to me more sensible if the SHAC didn't do this, and instead started with a non-zero value when ramping on.

 

I’m sure this is expected behaviour,
this is how cbus dimming is done, the on/255 or off/0 commands tell the dimmer output unit which way to dim up or down, subsequent ramp commands are sent after that.

Is it possible to filter out the 0 and 255 values and use them as a reference point?

 

Thanks Pie Boy. I don't think filtering would work with my script designed as an event.

I'm going to change it to be resident instead of event-based. That way I can watch over time to detect a 'ramp up' for my groups of interest and ignore the ramps down. I'll use the event to send over a group for the resident to add to a 'monitor list', which it could do for up to 30 seconds, or until no further movement in the level is seen. Using that approach would avoid constantly monitoring 63 groups.

 

Using a resident script will most likely use a lot of cpu for this… specially if you want a snappy result…

What about a way in which you can detect a ramp command on event
Like
rrate = tonumber(string.sub(event.datahex, 5 , 8),16)
Log(rrate)
Or
rrate = GetCBusRampRate(0, 56, 1)

I think when the on/off ramp command is issued it is issued as an on/off ramp it would have a value in the ramp rate) so Could be detected with a ramp rate value.

that’s off the top of my head so could be incorrect…

 

I really like that trick to get the ramp rate from event.datahex! And I also never noticed that GetCBusRampRate was a thing. Does that return the rate that a group is presently ramping at?

I ended up settling on the little resident nugget below, which works very, very well so far... In short, it looks for a level that hasn't changed for around three seconds, and if that's the case (and the level is non-zero) it sets a 'lastLevel' value to be saved.

This script gets fed by an event-based script that looks for level change that fires require('socket').udp():sendto(event.dst, '127.0.0.1', 5433), which causes this script to add a group to monitor.

Sleep interval is zero, but that doesn't bother the CPU because it's also looking for keep-alive messages on a UDP socket with 0.5 second timeout. CPU sitting at ~1.5 load with a bunch of other stuff happening.

Code:

--[[
Maintain CBus 'lastlevels'

Used so that MQTT 'on' events can return a light/fan/blind to the last known set level.

Also monitors keepalive messages from 'MQTT send', and disables/enables that script should it fail for whatever reason.
--]]

function loadLastLevel()
  lls = storage.get('lastLevel', '')
  llt = string.split(lls, ',')
  for _, v in ipairs(llt) do
    parts = string.split(v, '=')
    lastLevel[parts[1]] = tonumber(parts[2])
  end
end

if not initialised then
  logging = false

  server = require('socket').udp()
  server:settimeout(0.5)
  server:setsockname('127.0.0.1', 5433)

  monitoring = {}
  iterations = {}
  last = {}

  lastLevel = {}
  lastSaved = os.time()
  loadLastLevel()

  log('MQTT lastlevel initialised')

  initialised = true
end

function saveLastLevel()
  local ll = {}
  for k, v in pairs(lastLevel) do
    table.insert(ll, k..'='..v)
  end
  table.sort(ll)
  local lls = table.concat(ll, ',')
  old = storage.get('lastLevel', '')
  if lls ~= old then
      storage.set('lastLevel', lls)
    log('Saved last levels')
  end
end


remove = {}

for g, ts in pairs(monitoring) do
  parts = string.split(g, '/')
  net = tonumber(parts[1])
  app = tonumber(parts[2])
  grp = tonumber(parts[3])
  current = GetCBusLevel(net, app, grp)

  -- If the monitored group stays at the same level for six iterations then it's a stable value and not ramping (0.5s per iteration)
  if current == last[g] then
    if iterations[g] > 6 then
      table.insert(remove, g)
      if current > 0 then -- If the stable value is non-zero then save it as the lastLevel
        lastLevel[g] = current
        if logging then log('Setting lastLevel to '..current..' for '..g) end
        saveLastLevel()
      end
    else
      iterations[g] = iterations[g] + 1
    end
  else
    iterations[g] = 0 -- Level changed, so reset
    last[g] = current
  end
 
  if os.time() - ts > 30 then -- Level has been changing for more than 30 seconds, so terminate the monitor
    if logging then log('Terminating monitor for '..g..' (30 second timeout)') end
    table.insert(remove, g)
  end
end

for i=1,#remove do
  if logging then log('Stopping monitor for '..remove[i]..' at '..os.time()) end
  monitoring[remove[i]] = nil -- Clean up removed monitors
end


function contains(prefix, text)
  pos = text:find(prefix, 1, true)
  if pos then return pos >= 1 else return false end
end

-- Look for lastlevel values
cmd = server:receive()
if cmd and type(cmd) == 'string' then

  -- If the command contains a slash it's to start monitoring a group
  if contains('/', cmd) then
    -- processCommand(cmd)
    if not monitoring[cmd] then
      last[cmd] = -1
      iterations[cmd] = 0
      monitoring[cmd] = os.time()
      if logging then log('Starting monitor for '..cmd..' at '..os.time()) end
    end

  -- If it contains a plus then it's a heartbeat
  elseif contains('+', cmd) then
    parts = string.split(cmd, '+')
    if parts[1] == 'MQTTsend' then
      MQTTsendHeartbeat = tonumber(parts[2])
    end
  end
end


--[[
Heartbeats:

The MQTT send script infinite loop can fail, stopping that script. To ensure it gets
restarted without intervention, this script listens for a heartbeat from it every ten
seconds. If two consecutive heartbeats are not received then that script is disabled
and re-enabled.
--]]

-- If last heartbeat is nil (i.e. not yet received) then initialise it
if not MQTTsendHeartbeat then
  MQTTsendHeartbeat = os.time()
end

MQTTsendSecondsSince = os.time() - MQTTsendHeartbeat
if MQTTsendSecondsSince > 20 then -- Missed two heartbeats, so re-start script
  log('Missed two MQTT send heartbeats (last received '..MQTTsendSecondsSince..' seconds ago) - Re-starting MQTT send')
  script.disable('MQTT send')
  script.enable('MQTT send')
  MQTTsendHeartbeat = nil
end