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INDI Library v2.0.6 is Released (02 Feb 2024)

Bi-monthly release with minor bug fixes and improvements

USB_dewpoint v2: probe1 and ambient inverted?

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There's a weird behavior in USB_dewpoint v2 driver: both in manual and automatic mode when power is applied to an output (e.g. Channel 1), the ambient temperature goes up, the Channel 1 values remains stable and the Dewpoint increases.
That is strange because I would expect Channel 1 to increase, Ambient to stay (more or less) stable and Dewpoint stable.

Is it possible that values for Channel 1 and Ambient temperatures are inverted?
As a proof of this I tried to calculate dew point given temperature and humidity: using Humidity and Ambient (as it should be) I get a wrong dew point. Using Humidity and Channel 1 I get always the Dew Point shown by the driver.
Moreover as additional proof, in automatic mode, the heating never stops: Channel 1 doesn't increases, but Ambient increases and raises Dew point. So the gap between the two increases and power is always 100% and never stops.

My understanding is that as INDI driver just reads values from device, so it's not an INDI driver issue but a firmware issue (v 1705) on USB_dewpoint.
In fact dewpoint value is not calculated by the driver but read from the device.
Does anyone else experienced the same?

Thanks
Ferrante

PS: yes, I checked that I connected Ambient probe and Temp1 probe in the right positions on the device.

This is the order of parameter read by the INdi driver in usb_dewpoint.h:
// Status response is like:
// ##22.37/22.62/23.35/50.77/12.55/0/0/0/0/0/0/2/2/0/0/4**

// Fields are in order:
// temperature ch 1
// temperature ch 2
// temperature ambient
// relative humidity
// dew point
// output ch 1
// output ch 2
// output ch 3
// calibration ch 1
// calibration ch 2
// calibration ambient
// threshold ch 1
// threshold ch 2
// auto mode
// outputs ch 2 & 3 linked
// aggressivity
Last edit: 5 years 3 months ago by Ferrante Enriques.
5 years 3 months ago #32092

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Thanks for the report, I'll take a look, could be that I messed something up as well when reverse engineering the protocol.
The following user(s) said Thank You: Ferrante Enriques
5 years 3 months ago #32101

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thanks Jpaana, But consider that could be the device firmware and not the INDI driver.
I'm saying this because, in the spirit of INDI and briefly looking at USB_dewpoint.cpp, I guess you wrote the driver as a proxy of the device, without any further transformation on the data.
Dew Point is showing a wrong value and it is calculated inside the device not by the driver.
5 years 3 months ago #32102

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Yes, it just passes on the information from device's reply. I originally used the Windows software to control the device and captured the commands and responses so there might some error there. Have you checked if the Windows software behaves the same way? Yours does have a lot newer firmware than mine though, which is version 1446. I currently have the device at home and not at my observatory so I can test it. I don't have my dew heaters here, but I can warm the sensors up just by touching them, that's how I did it initially too :)
Last edit: 5 years 3 months ago by Jarno Paananen.
5 years 3 months ago #32108

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No I don't have any windows pc , so I didn't check it.
Yes my device is brand new and I think that 1705 is their latest firmware version. And the fact that with your older version it's working fine means that is likely an issue on device side.
I wrote to USB support.
5 years 3 months ago #32110

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Probably unrelated and different issue, but I experienced very strange read outs of ambient temperature (hundreds of degrees...) and humidity (see screenshot) from a brand new usb-dew point.
Support from the manufacturer was completely absent, so I sent mine back.



Sent from my iPhone using Tapatalk
5 years 3 months ago #32184

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I now tested this with my unit and all temperatures worked correctly and dew point was dependent on the ambient temperature and humidity as expected, so it might be an issue with the newer firmware then or if they have changed some other components in between.
5 years 3 months ago #32186

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Those sort of weird values happen on my unit too if the ambient/humidity sensor is not connected.
5 years 3 months ago #32187

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That was my thought too, so I pulled the sensor out and pushed it back in several times, but no luck.
5 years 3 months ago #32211

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Did anyone ever get an answer from USB_focus support?? I wrote them more than a week ago and unfortunately there's no phone contact on the website .
It's quite disappointing to have a device not working and no help from them.
5 years 3 months ago #32407

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