Ambient Temperature Sensor

[gm58]

Checklist

• I made sure that there are no existing issues or discussions - open issues,closed issues,open discussion, closed discussion - which may answer my question or that I could contribute my information to.
• I have read the Known Issues Wiki Page and my question / issue is not listed.
• I have provided the version of the software and the operating system in my post.
• If I have an issue with genmon not communicating with the controller, I have read and followed the serial troubleshooting guide.
• I have included the generator make and model in my submission.

Version

V1.19.07
OS Version: 11 (bullseye)

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I have not submitted logs

What is/are your question(s)?

I have a Generac 22KW, Model 704311, and was wondering if anyone has ever noticed the "Ambient Temperature Sensor" on the Maintenance page read anything colder than 0 deg F? At -17 deg this morning it only read 0 F

Additional information

No response

[jgyates]

Some background: The Evo2 is the only controller that displays this value on the Maintenance page. Some other controllers may show Ambient Temp "Display Experimental Data" is enabled but the value does not display to a temperature but what I guess is a voltage value that needs to be converted to temperature (which I don't know how to do since I don't know the thermistor or resistor values used in the circuit). I would guess the ambient temp reported in the Evo2 is based off a simple thermistor and this temp is only used to tune the start parameters based on how cold it is outside so I would not be surprised if it only a limited range of temperatures.

But to try to answer the original question, this modbus register does not return a signed value so the lowest number it can report is zero.

[gm58]

Appreciate the quick response, thanks!

[zinglo]

I was looking at an issue on my setup this evening. (We don't get that much freezing temps.)

I don't know if this is at all related since I am running a Briggs & Stratton... but any time my temps get below freezing, I get wonky numbers. I swear I looked at this and fixed it last winter, but here I am again.

In my case, the register for ambient temp looks like a signed negative number (currently 65532). Genmon reports it as "Ambient Temperature : 11827" -- as if the sign bit wasn't there at all. By my math, that should be -4 (or -0.4 after the multiplier). All works well for temps above freezing.

The tidbit in question in the json:

{
    "reg": "0034",
    "reg_type": "input",
    "mask": "ffff",
    "multiplier": 0.1,
    "type": "int",
    "signed16": true,
    "temperature": "celsius",
    "title": "Ambient Temperature"
  }

I realize this is a different issue entirely, so maybe I should start a new thread, but this one felt so warm and inviting.

[zinglo]

I'll resend regs again now that it is above freezing. It looks like reg 34 now has the value 0x24, which would be 3.6C. Genmon reports it as Ambient temperature 37 (farenheit) which seems pretty close.

[jgyates]

I checked in an update that should fix this issue. Let me know how your testing goes.

[zinglo]

Awesome, thank you very much. I grabbed/swapped out the custom_controller.py. (It looks like that was the change.)
It's 46F out right now, so it will be tonight or later this week before I trigger it. Thanks so much for your lightning fast response. I'll let you know how it goes.

[zinglo]

It took several really cold nights before I finally got ambient below freezing, but yes, works perfectly. Thank you very much.

[jgyates]

I am glad it is working correctly now. Thanks for letting me know.