By the way- RS232 signals swing between positive(3~11volts) and negative(3~11 volts) for it's logic states. ----- Original Message ----- From: James Cameron To: Sent: Saturday, July 22, 2000 8:30 AM Subject: [OT]: Help Wanted, UPS Interface > G'day, > > I'm trying to figure out the interface pinout for a uninteruptible > power supply (UPS) that I have. The unit came with no documentation, > and no interface cable, and I suspect that the cable may require some > pin remapping anyway. > > If you are willing to help, I've drafted a schematic of the circuit in > the UPS attached to the DB9. I've not gone beyond the optocouplers; I > got rapidly lost. I've also taken a few snapshots of the PCB. > > (220k of images) > > The UPS is straight analog; there are no digital components on the > PCB, no crystals, no microcontrollers (sadly), just bog standard > things like LM339's. I suspect therefore that the signalling from the > UPS to the PC is just "online" and "low battery", via modem status > lines. But there's a twist; there is an optocoupler facing the other > direction. I can't figure out what function it has. > > -- > James Cameron mailto:quozl@us.netrek.org http://quozl.netrek.org/ > > -- > http://www.piclist.com hint: The list server can filter out subtopics > (like ads or off topics) for you. See http://www.piclist.com/#topics -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.