[Nut-upsdev] driver for IVT SCD solar controller ?

Charles Lepple clepple at gmail.com
Tue Jul 28 23:15:35 UTC 2009

On Tue, Jul 28, 2009 at 5:23 PM, Rainer
Fuegenstein<rfu at kaneda.iguw.tuwien.ac.at> wrote:
> hi,
> I'm using the SCD-20 solar controller from IVT Gmbh in combination with a
> 230Ah battery and a photovoltaic panel to power a small server based on an
> Intel ATOM N270 CPU.
> the controller is (will be) connected to the server via RS232 (1200 8n1)
> and works like this:
> - if the battery voltage drops below 12V, a warning LED is switched on
> - if the battery voltage drops below 10.5V, the load (the server) is
> powered off to prevent exhaustive battery discharge
> - if the battery voltage raises above 12V, the power to the server is
> switched back on
> the info record delivered via RS232 looks like this:
> <R: current voltage; current power; current temperature; minimum voltage;
> maximum voltage; minimum power; maximum power; CRLF>

Is the "R:" an ASCII 'R' followed by a colon, or is that part of the
syntax for a record?

Also, do the records arrive on their own, or is there a query/response

> from the servers point of view the SCD works similar to an UPS:
> - if battery voltage is close to 10.5V, perform shutdown
> - if current power < 0, we are running on battery (power consumption is
> higher than power generated by the panel)
> - if current power > 0, the panel produces more energy than needed and
> also charges the battery

Sounds reasonable.

> questions:
> - is there already a driver which handles such a device ?
> - if not, which driver comes closest to this behaviour ?

I don't know of any off the top of my head, but it might be close to
one of the older drivers. Does the SCD documentation suggest any
specific monitoring software?

> - if none, is anybody willing/able to implement such a driver ?
> I'm willing to do the implementation, but my c/c++ programming skills are
> quite rusty ...

We can work with you on this. There is a skeleton driver, and the rest
will be adapting to the SCD protocol.

- Charles Lepple

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