Hi Garry,
I cannot find information anywhere on the SC2272T4. I can only find details of the SC2272M4 and the SC2272L4.
The ‘M’ stands for Momentary contacts, ie. the relay releases and soon as you stop keying, and the ‘L’ means the contacts are Latched until you press the button again.
When I looked back again at the ebay link you gave me, then I saw that the receiver was described as ‘self-locking’. So it looks like the ‘T’ is the same as the ‘L’ type. So you have now got several options:
1. You could replace the decoder with the momentary-contact type here
http://www.ebay.co.uk/itm/2PCS-PT2272-M ... 3a6d0f1ba3But that would appear to be almost as expensive as buying a complete new momentary remote.
2. Stay with what you have got, and:
a) Remember to press the same key again after the door has opened or closed, in order to deactivate the relay that has been activated. If you go down that route you should, ideally, wire a warning LED and limiting resistor across each of the limit switches. When the door had reached its limit the LED would then light up to remind you to press the button again.
OR:b) You could use a 555 timer and three resistors to remove the power from the receiver when a limit switch had been operated. That would cause the decoder to reset and automatically deactivate the relay. If you want to go that way, I will give you a revised wiring diagram.