Hi everyone,
we have been hired for a job which includes something that we don't have too much experience with. It's not rocket science, but I could use some critique/help.
We have to control some media players over a serial port, which we'll do with Teensies (probably 3.2). These media players will be installed in passenger elevator cabins, and will change the content that is displayed in sync with whatever the elevator cabin is doing (door open, going up, etc.).
For this we need to interface with the elevator's control unit. There will be a module with twenty active low 24V ouputs that sits on the control unit's main bus, and I am currently trying to figure out the best design for the interface board.
The main goals/requirements are:
The big question now is how to do it. Resistor dividers? No isolation. Relays? Big and expensive (not much of a budget for this aspect of the job). Optocouplers? I read somewhere that it's better for them not be on most of the time.
So, if anybody out there has experience with this kind of scenario, I would really appreciate their opinion.
Cheers,
Wolfgang
P.S.: If you need more information, I'll be happy to provide. I wanted to keep this short, to increase the chances of it actually being read...
we have been hired for a job which includes something that we don't have too much experience with. It's not rocket science, but I could use some critique/help.
We have to control some media players over a serial port, which we'll do with Teensies (probably 3.2). These media players will be installed in passenger elevator cabins, and will change the content that is displayed in sync with whatever the elevator cabin is doing (door open, going up, etc.).
For this we need to interface with the elevator's control unit. There will be a module with twenty active low 24V ouputs that sits on the control unit's main bus, and I am currently trying to figure out the best design for the interface board.
The main goals/requirements are:
- It needs to be simple. We'll only need three boards (plus a couple of spares), so I'll be populating and soldering these by hand.
- Reliability. It's not safety critical, but it needs to work.
The big question now is how to do it. Resistor dividers? No isolation. Relays? Big and expensive (not much of a budget for this aspect of the job). Optocouplers? I read somewhere that it's better for them not be on most of the time.
So, if anybody out there has experience with this kind of scenario, I would really appreciate their opinion.
Cheers,
Wolfgang
P.S.: If you need more information, I'll be happy to provide. I wanted to keep this short, to increase the chances of it actually being read...