Re: Nefit:can not set Room Setpoint?
Posted: Fri Sep 11, 2015 7:57 pm
But what happens if there is not an OTGW between master and slave? Th master is looking for a value for ID9 from the slave; where does the slave get it from?hvxl wrote:I'm not sure what you mean. ID 9 is a read parameter, so the thermostat wants to read it from the opentherm slave device it talks to. When using an OTGW, that's the gateway. So the gateway can return a value. No problem. It works with several thermostats.
It's the descriptions bit (!!) which didn't make sense. But I've now worked out what it means!I also don't see what doesn't make sense about ID100.
No problem. I had overlooked the fact that we are talking about a RF OT stat.I don't think the picture on page 8 applies to the current topic. The OT interface part of CMT957M1011 doesn't sit between two opentherm connections. It talks OpenTherm toward the boiler (or OTGW) and probably some proprietary protocol on the RF interface. So, as far as opentherm is concerned, the R8810A1018 is (represents) the room controller. Unless I misunderstand what you mean.
As for the RF communication protocol, I found the in a OT newsletter from 2009, which has escaped into the wild:
OpenTherm KNX RF Solution
The taskforce RF is coming to a close soon with the release of the standard for OpenTherm over KNX RF. As soon as we have documents they will be distributed to all
the members. The board of OpenTherm considers the RF solution with KNX as a considerable contribution to the protocol. However there are also other possibilities
when it comes to wireless communication. The board therefore welcomes new taskforces for for instance Zigbee, Z-wave and other relevant solutions.
Honeywell, of course, may have done their own thing.
As for how a remote thermostat communicates with the 'master' stat, I was thinking generally, not specifically about the OTGW. You need a way of generating ID9 by reading the required temperature from the remote thermostat. I am suggesting that this could be accomplished by having an arrangement as in the picture with the remote thermostat connected to the "other interface". Of course this might be achieved by modifying, if possible, the OTGW to take a second thermostat input. (Presumably wireless communication - (internet?) -if the remote stat is in another building miles away from the master.)