Humidistat Fan Control

Hi Guys,

This will pretty much complete the project until I connect the c-touch and put together any pascal or irrigation control I could need help with.

What I want to do :

I have a humidistat sensor which I will use for controlling a fan I would also like to have a key input to overide the fan off/on for a period of time say 1 or 2 hours.

My current "bench" setup am using a bridge to link the input on an aux input unit (group "Laundry Fan") and the timer programmed through this. I also have a dlt with and input using the same group. The problem I face which does not present in an almost identical hallway pir setup (as the pir input is always momentary) is:

The fan output starts and whilst the bridge remains connected continues running (timer not started), the moment the bridge is removed the timer starts and if the bridge is ever held on again the timer continues without "holding the circuit closed" as it does on the initial short or long press. (I imagine a humidistat could cycle a bit with varying humidity at the switch point - it says it has a 4% differential which may solve a lot of nuisance. Though i'd prefer 10 or a variable diff.) The only work around I see for this is to create a length of time long enough that any steam etc would definately be vented.

However the part I am finding hardest is to create a dlt input that will eaither turn on the fan for say 15 mins or turn off the fan for 2 hours. Is there any easy way of working with one button to perform this or would I be better of waiting till I can use pascal to "if fan currently on turn off for 2 hours/if fan currently off turn on for 15mins".

The main reason for requiring something like this is that if the humidistat is in the closed state the aux input will only see it on change of state (not in the permanently held on state). If I programmed a dlt to turn the unit off and go idle after a period of time the fan will not switch back on the sensor will be closed and only human interaction will start the loop again.

This almost sounds like a plc loop.

Please tell me if i'm thinking illogically or is that too logically?

 

All in all pretty much the fact the aux input doesn't see a held input has stumped me and I'm buggered if I can get my head around it.

Any help would be most appreciated.

Cheers.

 

From what i can tell I could invoke a timer from a single dlt button that will turn on after short press/off with long and timer on each retriggering on the releases. However issuing off after the timing the aux input will not reclose if the input is held on.

 

Sorry for replying on my own post b4 anyone has even commented but I can use a second dlt (one for off and another for on) which would enable logic functions if I could use combinations of and/or statements however there is only and or or for use in each outputs expression as far as I can tell.

....ok will stop replying for a while now ........... either have to stop drinking and concentrate on it or keep drinking and forget about it lol


Cheers

 

Wouldn't a long press set to On (or whatever) do the trick. Set the short press, short release and long release to idle. One the input has been on for more than 400ms (a long press) the command should be issues. The release will do nothing as it is set to idle.

Mick

 

What you propose would work however; I was going to use a timer on the circuit to stop the potential nuisance cycling that could occur. The 4% differential may be enough to prevent too many stop starts though.

Will give the method put forward by you a go and let you know how it goes.

Will also use a key input to time an on or off cycle at 30 mins for overide control.

Will a key configured short press "on" short release "retrigger" long press "off" long release "retrigger" and an expiry event of "off" at a timer of 30 mins let one key time on and off for 30 work? Understand I may have to extend the long press to a longer time to aid it's effectiveness if this will work.

If I have issues with cycling I will try and pascal it out later down the track.

Thanks for the help.

 

not sure if I'm on the right track or not, but here goes..

The timer function in ANY C-Bus key, PIR, Bus coupler or aux. input can be programmed to start a timer at any one of 4 distinct 'key press stages'

there are two timer types: START simply loads a down-counter with the appropriate time for that group, and RETRIG does the same but ONLY IF the group was in the ON state when the command issues (RETRIG is intended for PIR sensors so they can hold a load in the ON state even if the ambient brightness is higher than the normal limit, which would happen if the PIR is close enough to the lights that it controls). In either case, when the down-counter counts down to zero at a rate of one count per second, the timer expiry command will issue.

I suspect that you want to use the START timer.

Now the state of the group is NOT affected by the timer activity (NB. early C-Bus units, with Firmware version 1.00 would respond to START function by turning ON the group associated with the key, but all later key units do not affect the group state with START), so you would also need an ONKEY, UP or a RECALL to set the group state on

In the following, I use the label "Just Pressed" for the first key press stage rather than "Short Press", because
I think it more accurately reflects the behaviour of the stage; just pressed will issue for both 'short' and 'long' presses.

just pressed command will issue with each key press or contact closure in the case of aux. input
short release command will only issue if the key is released before the long press time (400ms nom.)
long press command will issue only if the key is held longer than the long press time
long release will only issue if the key is released after being hels for longer than the long press time.

so you see, you get either: jp and sr if you press a button for a time less than the Long Press Time

- OR -

you get jp, lp and lr if you press a button for long press time or longer.

If you set up the following:
just pressed = onkey - load is turned on
short release = start - load will remain on until the timer expires
long press = start - load will remain on until the timer expires
long release = idle - do nothing

timer expiry command = offkey

now if the the sensor is bridged to the aux input, when the humidity exceeds the threshold, the aux input will start the fan, and the fan will run for the run time. This will happen even if the contact is held closed.

If the humidity drops below the threshold while the fan is running, nothing will happen with the above setup. If you want the fan to stop in that case as well, before the timeout, you can change the idle to an offkey for the long release key command

does that help?

 

Thanx Don, that definitely helps me understand more clearly.

The only other question that still remains in my mind is if I use an overiding single key input like follows - and yes I did stuff up my previous post with retrig instead of start:

Key input (Single key) operating same group tag as the fan setup you gave.

Block timer set on 30 mins

short press - on key
short release - retrig
long press - start
long release - off

expiry - key off

Would this overide the aux input with a start on short press - duration 30mins and stop on long press duration 30 mins? The only problem I could see with what I just wrote is if the key input issues the command (ie the aux input sees high humidity and is running and it's winter and I am freezing my tits off) and I press the key for a long press to overide it off. Once the timer times out the expiry of off will be executed and the fan will be off even though the humidistat is still giving a closed circuit.

Or does the aux input restart? - I tried to simulate it on the bench but the aux-in appeared to only see the input on changing (not a held contact).

I presume it does this in order to determine short and long presses - though a held contact in my opinion would be the same as long press.

I am sorry to be asking a question that I can't put into practise atm as I am on shift and don't get much time to play with my setup.


Cheers,

I really appreciate the help and hope that one day when I lose my newbinity I can return the favour helping others.

 

when pressing keys or accepting contact closures in the case of an aux. input, the unit will issue commands on the bus only in response to either changes in key / contact state/ or due to expiry of long press time in the case of the key / contact remaining closed for a 'long' time. This means if the sensor keeps the contact closed to the aux. input, and you over-ride the group state from a key unit (after the long press time of the aux. unit), the aux. input will not do anything else. This sounds like the behaviour you are after.

Also,

Any command that issues on the C-Bus network will stop any timers active in all units controlling the group affected by the command except any timers in the unit that sent the command. This means if you start a timer in an aux unit, then use a key unit to change state of the load, the timer in the aux input will be stopped. The last unit to issue a command to the bus is always the unit that is in control.

Be careful here: if the group state is OFF already, and an OFFKEY key press is sues, no command will issue on the bus. Similaryly, ONKEY will not issue if the group is already in the ON state. If you want a positive command that will issue irrespective of the state in order to cancel timers, use RECALL and RAMPOFF commands. to turn a grou ON and OFF respectively.

 

Thanx very much for the help - the last post has helped me undertsand the underlying structure of the control hierachy. I think if I want to use what I was after I would need to go to pascal - though having not been able to put it into practice the system you first laid out will possibly work given that if the overide is used the humidity will drop to below the trigger point stopping any stuck off system. (In the case of the held aux contact - due to humidity not dropping far enough to rest the contacts).

I have a much clearer understanding of what is occuring now.

Cheers.

 

Have made this up let me know what u reckon.

http://www.cbusforums.com/forums/showthread.php?t=3821

cheers