Your dome stays safe even if the computer freezes

Being able to use the CloudWatcher as a watchdog—«watching» PC activity, and closing the relay in case the PC freezes—is a well known CloudWatcher feature. But one happy user, Vincent Steinmetz, drew our attention to another option, described below.

How the watchdog works

The CloudWatcher and your PC maintain an ongoing dialog. If the PC freezes, that dialog stops, the CloudWatcher notices the PC has gone silent, and it closes the relay—so the dome can be closed without any software being involved.

Watchdog sequence: what happens when the PC freezes

1
PC running normally Automation software is in ongoing dialog with the CloudWatcher.
!
PC freezes or loses power The dialog stops. CloudWatcher receives no further communication from the PC.
2
CloudWatcher detects silence The CloudWatcher sees no further PC activity on the link.
✓
Relay closes → dome closes The CloudWatcher closes the relay, so the dome can be closed. Equipment is safe.

The other option: an AC power fail feature

Vincent's observation concerns a different setting: the "UNKNOWN generates UNSAFE" option in the CloudWatcher software. With it checked, the software turns a loss of dialog with the CloudWatcher into an UNSAFE event.

That gives you an AC power fail feature, provided your CloudWatcher is on ordinary house supply rather than an uninterruptible power system: no power ⇒ no dialog ⇒ UNSAFE. A PC running on a backup inverter keeps going, gets the UNSAFE event, and closes the dome.

As Vincent puts it, this is really interesting for remote installations—where you cannot be physically present to intervene if something goes wrong overnight.

I just noted some nice unexpected feature in the cloudwatcher.

If the user checks ‘UNKNOWN generates UNSAFE’, the cloudwatcher makes a nice «AC power fail feature».

No power => No dialog => UNSAFE

It is really interesting for remote.

In our installation the cloudwatcher is on the house supply (not on a uninterruptible power system), so in case of power loss, the computer that operates on a backup inverter gets the UNSAFE event, and closes the dome (closing system is also on battery).

This is important enough to be mentioned in the documentation and advertising.

I discovered this the christmas night, the dome was operating alone, and we loss dialog on everything next morning, power has come again, and I saw the scope was nicely parked, and dome closed because of the cloudwatcher alert script.

You have a nice product there, it is really fine now!

— Vincent Steinmetz, CloudWatcher user

Thank you Vincent, a nice idea indeed!

Sexto, a brown dog, lying on a tiled floor with his head resting on his paws, looking up at the camera
Sexto, the other kind of watchdog. Rather less useful for closing roofs.

What you need to set this up

  • A CloudWatcher connected to your observatory PC—any model, this works across all hardware revisions
  • CloudWatcher software running on the PC, with «UNKNOWN generates UNSAFE» enabled
  • A dome controller or relay connected to the CloudWatcher relay output
  • For power-fail protection: a UPS or backup inverter powering your PC (and whatever closes the dome), so it keeps running and can react after the CloudWatcher itself loses mains power