TFA wind sensor

[stuiow]

Quick question, what units do the tfa anemometers output in, MPH/KPH/MS?
Cheers

Sent from my SM-G955F using Tapatalk

[ds106]

Hi,
Ruud v Gessel's "Cresta weather sensor protocol" describes Windspeed and Windgust as mph. As I can see RFLink passes sensor mph value as kmph to domoticz, rfxcom passes calculated kmph from sensor mph.

Win1.jpg (35.7 KiB) Viewed 3494 times

Regards Götz

[koenkooi]

Domoticz seems to do something different here:

It gets '8' as data:

Schermafbeelding 2018-11-12 om 14.53.04.png (22.88 KiB) Viewed 3251 times

And displays '2.9 km/h'

Schermafbeelding 2018-11-12 om 14.53.10.png (50.42 KiB) Viewed 3251 times

The code has this:

Code: Select all

        //Wind
        if (m_windunit == WINDUNIT_MS)
        {
                m_windsign = "m/s";
                m_windscale = 0.1f;
        }
        else if (m_windunit == WINDUNIT_KMH)
        {
                m_windsign = "km/h";
                m_windscale = 0.36f;
        }
        else if (m_windunit == WINDUNIT_MPH)
        {
                m_windsign = "mph";
                m_windscale = 0.223693629205f;
        }
        else if (m_windunit == WINDUNIT_Knots)
        {
                m_windsign = "kn";
                m_windscale = 0.1943844492457398f;
        }
        else if (m_windunit == WINDUNIT_Beaufort)
        {
                m_windsign = "bf";
                m_windscale = 1;
        }

Why does domoticz think the data is in decimeters/second?

[Toulon7559]

In Domoticz speed expressed as 0.1m/s is aspect of definition.
See https://www.domoticz.com/wiki/Domoticz_ ... L%27s#Wind
Only reason I could imagine, is that then the practical transfer values can be expressed as integers.

[koenkooi]

So is the '8' in the data overview the value read from rfxcom (presumably in km/h) or the processed value? I ask because the '8' is a lot closer to the 10km/h from the local weather report than the 2.9km/h domoticz displays.
I don't have a different (calibrated) anemometer to compare against, so domoticz could be doing the right thing already.

[Toulon7559]

If you are using Nexus' USB-interface, that interface is according to TE923:
this documentation might apply for read-out.
Reading this documentation indirectly you can find practical info on Nexus' data protocol.

[koenkooi]

I'm using the 433MHz sensors with an rfxcom transceiver connected to domoticz.

[sincze]

I noticed the difference as well and notified the stunt team on 28_7_18 unfortunately no response. But hopefully fixed in r49.

Windmeter.JPG (64.84 KiB) Viewed 3123 times

[Toulon7559]

@stuiow

Which interface are you applying to read the TFA_Nexus anemometer?

By accident (while looking for something completely different) I can confirm the observation by ds106 that in Domoticz it seems to make difference over which interface you read windspeed from TFA_Nexus
a) over the Console's TE923 USB-interface, or
b) wireless by RFXCom or
c) wireless by RFLinkGateway:
- the readouts a) and b) from the TE923-interface, respectively from the RFXCom usually agree
- the readout c) through the RFLinkGateway [in my case R46] shows much lower values [meanwhile this 'possible bug' reported to Stuntteam], possibly (?) a factor 1.6 due to output as mph vs. kmh

Furthermore, (similar to reported by sincze) generally the values coming from my TFA_Nexus' anemometer are lower than those coming from a co-located WS7000-anemometer (which I better trust, because better quality, although aged).

Just raises the question: which wind speed is true & correct?