Hi, I'm new to all of this so please bear with. I'm looking to switch a heater controller on, then off again 1 hour later. The controller requires a 1 second pulse to switch on, then a 5 second pulse to switch off. I'm hoping I can use an arduino for this. Basically a gsm switch needs to trigger the sequence, so the arduino will receive a 1 second pulse from the gsm relay, then nothing further. Is this at all possible? And how would I go about connecting this?
TIA
Well now, you first need to explain just what sort of "1 second pulse" is required by the controller, what connections are to be made to it, and what you believe a "gsm switch" actually is.
Paul__B:
Well now, you first need to explain just what sort of "1 second pulse" is required by the controller, what connections are to be made to it, and what you believe a "gsm switch" actually is.
The pulse required by the heater controller is basically connecting 2 pins together, there is a push button on the controller that I will tap into.
The gsm switch is a 6 relay board controlled by an sms or phone call, the signal I will send will be via sms for the gsm to contact a relay for 1 second. I'm hoping this can trigger the arduino to start the sequence.
Well, clearly an Arduino can do this, a Pro Mini would be the appropriate device or a Nano if you do not fancy getting the USB-serial adapter just to program the Pro Mini. (Please, not a UNO! 
)
As you need a relay to make the connection on the heater controller (thought an opto-coupler might be able to do it - you would have to measure how much current is drawn by that connection), it would probably be more appropriate to connect the Pro Mini between the GSM device and the relay driving transistor on that relay board and make use of the relay already there. 
I'm very likely missing something, but if the incoming sms triggers the gsm switch for a second, why can't that just be the same 1 second signal that the heater is expecting? What's the Arduino for?
If all that happens on the heater is that button is metaphorically pressed, can't the button's wires be brought to the relay's n.o and com outputs? The incoming sms activates the relay for a second, and that shorts the button.
Am I missing something?
12Stepper:
Am I missing something?
Gobigorgohome:
The controller requires a 1 second pulse to switch on, then a 5 second pulse to switch off.
Yes I know; I meant am I missing something that prevents the pulse (either one) just being squirted into the controller by the gsm switch? Be it a 1s or 5s pulse, if the gsm switch can give that pulse to the Arduino, so that the Arduino pulse the controller, why can't the controller hang off the gsm switch with no Arduino in the middle.
What I'm missing (assumimg I am missing anything) is the need for an Arduino in the first place.
12Stepper:
Yes I know; I meant am I missing something that prevents the pulse (either one) just being squirted into the controller by the gsm switch? Be it a 1s or 5s pulse, if the gsm switch can give that pulse to the Arduino, so that the Arduino pulse the controller, why can't the controller hang off the gsm switch with no Arduino in the middle.What I'm missing (assumimg I am missing anything) is the need for an Arduino in the first place.
The gsm could trigger the heater control, but that would just turn the heater on indefinitely. I want the heater to be active for an hour and then be switched off.
Why can't the gsm switch give the heater the 5s off pulse?
12Stepper:
Why can't the gsm switch give the heater the 5s off pulse?
It can, but then I'd have to remember to send the command. I want to be able to send an on command and forget about it. As far as I know, there's no wait command on a gsm switch.
Gobigorgohome:
I want to be able to send an on command and forget about it.
Told you I was missing something: that was it.
Ok carry on, don't mind me 