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I would like to design a simple relay which is triggered by a series of pulses rather than just a high signal.

e.g. the relay would have a serial data input. The relay would need to be "preset" with the code which will trigger it - e.g. 119. Then if you send it 01110111, the relay latches. Then sending a reset code (or the same code) could unlatch it.

I know this would be a fairly simple logic circuit to make, to drive a standard relay, but I'm wondering if such a product already exists, what it would be called so I can find it in component catalogues.

Update: the signal would be sent from an existing system which can be programmed to send pretty much any digital signal sequence (e.g. faking RS232 or other encodings) but only has one output line, and I can add line level conversion if needed.

Update 2: as I only have one driving line, I cannot provide a clock signal, so it must be asynchronous serial.

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    \$\begingroup\$ The gadget you are looking for is called a "microcontroller". You just need to write the code for your desired function. Any more specific information would be a shopping question, which is off-topic on this site. \$\endgroup\$ – Elliot Alderson Jan 7 at 3:05
  • \$\begingroup\$ @ElliotAlderson As I mentioned I could build this in logic, so I don't need an MCU. \$\endgroup\$ – scipilot Jan 7 at 3:26
  • \$\begingroup\$ How will the user send the value 01110111? Keypad, switches, ...? \$\endgroup\$ – Yoshimitsu Jan 7 at 4:13
  • \$\begingroup\$ What are the two codes you've settled on. Or are you flexible on that? \$\endgroup\$ – jonk Jan 7 at 4:26
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    \$\begingroup\$ consider using a standard remote control decoder chip, eg HT12D \$\endgroup\$ – Bruce Abbott Jan 7 at 6:37
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I know this would be a fairly simple logic circuit to make, ... but I'm wondering if such a product already exists, ...

It probably doesn't exist.
When you have the luxury of one or more wires you'd typically use a versatile or robust solution.
One which offers more than just unsolicited command shouting, such as I2C.
One that isn't as susceptible to noise as a single ended wire. Such as RS-485.
One which layer 2 protocol contains data integrity checks, such as CAN-bus or MODBUS-RTU.

Shouting 01110111 over a wire won't be a suitable solution in the industry for obvious reasons.
It is however widely used in cheap 433 MHz remote control sockets. A set of dip switches then configures the numbers it will listen to.

enter image description here

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  • \$\begingroup\$ Yes, I am using RS424, 232 and other protocols in other areas but in this case I am limited. I guess this question should be re-posted as what is a reliable single-wire protocol now I know there's no such relay. \$\endgroup\$ – scipilot Jan 8 at 2:57

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