USB Controlled Power switch

[tenjeeuk]

Firstly, so nice to be able to post on here again after the loss of the Demon newsgroup server robbed me of easy access via ThunderBird.

I am looking for a USB/PC controlled power switch to enable 1 device ( a large format topuch screen ) to be switched off/on.

We use a RS232 control through the PC but there is an intermittant fault that causes teh screen to become unrepsonisve, and requires a hard power down.

Problem is the screen has been installed in a manner that makes it impossible to access teh on/off button.

So one possible slution is a power switch controlled by the PC.

I'd prefer USB rather than LAN/network controlled switch as that would be more secure.

I posted here because I thought if anyone has played with this stuff it would most likely be someone on here.

[Bob Eager]

Google 'USB relay' and there are loads. Most are mains rated.

[tenjeeuk]

@Bob Eager.

Thanks Bob. I'd prefer something more commercially finished than one that is just some exposed circuitry.

[dennis]

Would one of these do, and stick the remote next to the PC.

[Theo]

I've had good experiences with Raspberry Pi remote switches (and power measurement in fancier versions):

Theo

[Dave Liquorice]

I suspect that the easy to access buttons might be an issue for the OP. Of course one could hijack a couple of the RS232 control lines to operate a transistor switch across the on and off pads of the remotes PCB.

But if you're going to do that why bother with all the RF malarky. Just use an RS232 control line to operate a mains relay. Still need a transistor switch to drive the relay.

Both Fail the "boxed and ready to use" test though. B-(

[Brian Gaff]

To be honest, surely if the switch is dodgy the best thing is to fix it no matter how much dismantling and remantling is needed. Faults tend to get worse and a bodge now will haunt you later on. Brian

[Dave Liquorice]

That's one way of reading what was written. I read it to mean that the screen occasionally crashes and needs a power cycle to reset it.

[tenjeeuk]

The issue is with the RS232 becoming unresponsive after a few days of runni ng normally. The only way to reset to back so it waorks again is to power o ff/on. Unfortunately the screen has been installed in such a way that acces s to the power switch is not possible. They even don't execatly know which mains plug it connects to.

So, I am exploring a workable solution, not neceassry the best.

[harry]

ning normally. The only way to reset to back so it waorks again is to power off/on. Unfortunately the screen has been installed in such a way that acc ess to the power switch is not possible. They even don't execatly know whic h mains plug it connects to.

You need to be able to isolate it from the mains power supply.

[Dave Liquorice]

To clarify the screen is linked to a PC via an RS232 connection. This link stops working after a while and power cycling the screen brings it back.

Is this RS232 link directly between RS232 ports on the screen and PC or is there a USB to RS232 dongle in there somewhere?

Not all USB to RS232 dongles are created equal. I use one between the UPS (RS232) and server (USB). The first one I bought would spontaneously disconnect the USB side, immediatly reconnect but the communications would never re-establish. This would happen about once a month.

Bought another USB to RS232 dongle about a year ago using a different chipset and it's not happened again...

Poor one: Prolific PL2303 based Good one: FTDI FT232RL based