Untangling MQTT Broker values

[crfrancis]

The physical distance from my camera/sensor head to the R-Pi running INDI-AllSky (in the observatory) is too far for I2C or One-Wire interfaces to be reliable. So I have a little Arduino in the sensor head connected to the relevant sensors, and it sends its data via an MQTT Broker on another Pi in the observatory.

There are 5 variables from both a SHT31 mounted outside and a Melexis medium beamwidth IR sensor inside. They are external temperature and RH, plus computed dew point, internal temperature and the IR temperature of the dome (the emissivity of acrylic is close to 1 in the region of the iR used by the Melexis sensor and I've verified it gives a representative temperature).

As far as I understand the Sensors tab I must put all the MQTT parameters in one slot (so I have the 5 parameters named in the Label filed, and the 5 topics in the Pin/Port field, all associated with Sensor A slot (User Slot 10). In the Charts I can only find 4 of these parameters (and I haven't found out how to show the 5th), but in each case they are identified as "MSTT Broker - [list of parameters] - Value 1" etc.

I don't see how I can extract either the dew point or the humidity to use to drive the dew heater.

[aaronwmorris]

There is just currently a limit of 4 custom graph slots. I could add another graph or two.

If one of the MQTT values is the dew point, you should be able to configure that MQTT value slot on the dew heater configuration as the data value to use for the thresholds. Assuming the MQTT sensor is configured for slot 10, the MQTT sensor will return 5 values, starting at slot 10. The 5 values will be in slots 10, 11, 12, 13, and 14.

[crfrancis]

One more graph would be good -- there are 5 slots for values so 5 graphs would be appropriate.

On extracting the values from the MQTT stream, yes, now I see that I can select each of them. But I still have a problem: I want to compare the measured dome temperature to the measured/calculated dew point. I can put the dome temperature in the "Temperature Sensor Slot" in the Enable Dew Heater Thresholds on the Devices tab, but there is nowhere I can declare the source of the dew point, here or on the Sensors tab.

And in fact I want to add a delta, so the dome is kept above the dew point, say by 5 degrees (given measurement uncertainties etc.). I don't see a place where I could add such a delta either (unless I code it into the Arduino, which is not very flexible as I'd have to disassemble the all-sky camera to reprogram it).

[aaronwmorris]

Merged #1767 which includes 2 additional custom graphs.

I have also added a new selection to override which value is used for the dew point. The delta can be configured in the Low/Med/High difference values.

[crfrancis]

Great, thanks for the quick response. I'm always impressed at your speed in responding to these things.

This solves all the problems associated with controlling the dew heater.

For the graphs I'm not out of the woods yet. I added the 5th data value to the graphs, but when selecting Charts, all graphs were blank with a message "Error loading data. Please check the logs". The only logs I can find are in indi-allsky/log, and there is nothing useful there.

Any idea what's wrong with?

[aaronwmorris]

Merged #1768 . I thought I had tested enough, but I just missed this. This should fix things.

[crfrancis]

OK, this nails it!

Thanks !