Automating ZWO ASI2600MM Dew Heater with NINA

I just leave it on even though I’m in a dry climate. Better safe than sorry.

Quinn Groessl:
I use a Pegasus Powerbox, looking at the equipment in your photos I think you do too. So if you have that and their temperature/humidity sensor, you can just use their software and leave it on auto.

Like Rick, I just set it, and forget it.

For the longest time I was a bit paranoid about it running on its own. But I grew up and decided to trust it while it is, after all, covered by ZWO warranty. (Which ain’t saying much in my experience.)

I have it on in NINA. No Problems. Let the camera decide.

Rick Krejci:
I understand what you’re trying to do and why, but unfortunately I don’t think there’s a way to automate it in Nina.

Rick Krejci:
I asked chatgpt, and it pointed me to the post below in a thread on CN that, if you use the native driver,there’s a command to do it in a sequence. If that’s the case, you should be able to use the sequencer powerup plugins and set temp and humidity/dewpoint in variables and use the delta to turn it on and off.

I no longer have a Zwo camera (moved to Player one) so I can’t see if there’s an advanced sequence command to do it.

https://www.cloudynights.com/forums/topic/929173-nina-and-dew-heater/#findComment-13564691

I just tried this in Nina and it works!

I use OpenWeatherMap as my weather source, and it provides Temperature and DewPoint

📷 temp2.jpg

Jerry Gerber · Jan 8, 2026, 12:20 AM

I know how to tell the camera to turn on and off the dew heater with Sequencer Powerups but I don't know how to link it to the humidity..

If you have a weather device set up in nina, you could use powerups triggers based on an expression which uses the weather humidity (exposed as a variable automatically) to turn on/off the dew heater.

If you hover over the white “i” in a circle on the left, it will list all of the parameters available. Just type them just as they appear there. In this case Temperature and DewPoint were defined in the weather column.

This made me think that I’ve recently added my own weather station to WeatherUnderground, so I added it to the weather option instead of OpenWeatherMap and connected. So now my temp and humidity are from a station 20 feet from my scope :)

You may be able to get it from your pegasus box if it’s listed in the hover parameters.

Jerry Gerber · Jan 8, 2026, 02:03 AM

Where can I learn to set up an expression?

Powerups documentation may be a bit cryptic at times, but it’s very useful. I myself would implement this as a When trigger probably: https://marcblank.github.io/CVE/#when. Rick provided good hints about the expression(s) you want to use.

Rostokko · Jan 8, 2026, 02:15 AM

Jerry Gerber · Jan 8, 2026, 02:03 AM

Where can I learn to set up an expression?

Powerups documentation may be a bit cryptic at times, but it’s very useful. I myself would implement this as a When trigger probably: https://marcblank.github.io/CVE/#when. Rick provided good hints about the expression(s) you want to use.

Yea, you’re right on the when trigger if you want it in the trigger section. I’m very new (weeks) to the powerups, so learning a lot today.

Jerry Gerber · Jan 8, 2026, 02:47 AM

Here's what I've done. 

It's working.  Fantastic...

After reading the powerup docs, I guess I’m surprised that would work continually being in the global triggers section. I think Rostokko’s suggestion of using a when trigger which would execute between each instruction without it being in the instruction section would be appropriate. If I understand correctly, the if statements would normally be in the instruction area and be executed sequentially with other instructions there rather than continually in the triggers section.

Jerry Gerber · Jan 8, 2026 at 03:30 AM

Rick Krejci:

Rostokko · Jan 8, 2026, 02:15 AM

Jerry Gerber · Jan 8, 2026, 02:03 AM

Where can I learn to set up an expression?

Powerups documentation may be a bit cryptic at times, but it’s very useful. I myself would implement this as a When trigger probably: https://marcblank.github.io/CVE/#when. Rick provided good hints about the expression(s) you want to use.

Yea, you’re right on the when trigger if you want it in the trigger section. I’m very new (weeks) to the powerups, so learning a lot today.

Jerry Gerber · Jan 8, 2026, 02:47 AM

Here's what I've done. 

It's working.  Fantastic...

After reading the powerup docs, I guess I’m surprised that would work continually being in the global triggers section. I think Rostokko’s suggestion of using a when trigger which would execute between each instruction without it being in the instruction section would be appropriate. If I understand correctly, the if statements would normally be in the instruction area and be executed sequentially with other instructions there rather than continually in the triggers section.

Yes, I see what you mean, that's the question I started thinking about.  In the Global Triggers section, I think it would only work once, at the start of the sequence.  When I try and drag "WHEN" to the anywhere in the sequence nothing happens...

You can’t drag “when” to the triggers section? That’s where it should go. There it will be evaluated and the associated instruction would run between each instruction in the main section. I would also put a little more space between the on and off condition in case the humidity is fluctuation right at the edge. Give it like a 1% buffer between on and off.

I think you’ll need another to turn it off, maybe at <63