Control / enable output only if logic running & connected to c-bus

Guys,

Is there a way to use GA as well as the AND logic in a relay module to ensure logic is running?

The reason i ask is i have an under tile heating system in my ensuite that is controlled from CTC & logic switching based on schedule & temp setpoint on CTC.

Today, i came home and found my CTC had been turned off, however the ensuite floor could fry an egg... what i am guessing has happened is that the CTC had been turned off at a point in time where the GA for the output was ON, and it remained in that state until the CTC powered up and connected again.... logic controlling floor temp sensor vs. setpoint then sensibly turned it off.

Ideally i would like to add some sort of condition that would have the output turn OFF if the logic is not running / disconnected, however my fear is when i assign a GA to this, it will also hold its last state on disconnection.

Any ideas?

Thanks

Grant

 

Hi ICS-GS,

Without spending much time considering this, one possible solution might be as follows.

Often there is more than one unit on a C-Bus network with a logic engine. If this is the case with your network, then you might:
- Use an enabling GA ANDed with your relay output at the relay, as you suggested.
- Have a second device with logic engine checking for periodic heartbeat responses from your CTC, and if if fails to receive them within an expected time frame, it sets the GA low.
- Do the same thing on your CTC, checking for heartbeat responses from your second logic engine device, and also setting the GA low if it fails to receive them.

If either device on its own fails or is disconnected from the C-Bus, then the other device will disable your heater. However, if both devices fail at the same time this approach would not help, so you would need to make an effort to make the power supply and C-Bus connection to the two devices as independent as possible - and make those of one of these devices as closely associated with the C-Bus output relay as possible.

 

Thanks Brendan,
Thats what i thought, but right now only have 1 off logic in CTC... so im buggered then?

Cheers

Grant

 

Hi Grant,

You don't have a Wiser (with logic engine) on your C-Bus network as well as the CTC?

 

How about if you turn the GA on then issue a ramp off function over say a 5 minute period with the relay threshold set to 1. Every 4 minutes or so the logic repeats the command. If the logic goes away, the relay will ramp off within 5 minutes.

 

Good one Ashleigh, ill see how it goes.

Thanks

Grant

 

Works a treat, thanks... however rather than waiting for a time period to reset ramp off, just looked at level = 10% to then set GA back to ON, then ramp off again.

Thanks

Grant