Ness/ELK M1 Levels & percentages bug.

Hi Nick,
Thank you so much for your offer of help. Perhaps I could explain my unique application first.

I and many other people use a home automation system called Homeseer (www.homeseer.com). There is a plugin that connects Homeseer to the M1 called UltraM1G3 which uses the ethernet gateway (ELK-M1XEP). Homeseer can see and control all the zones, outputs, keypads, users, counters, lighting groups, and audio zones from the M1.

The problem for me is that the only thing that the M1 can control on the C-Bus network (via the NESS M1 C-Bus interface) is the lighting groups (application 56). But I also have c-bus thermostats which the M1 can't see by itself. So I use a PICED to replicate the temperatures, setpoints and operations from the heating application to phantom groups on the lighting application and vice versa. I wrote some code to do this. So in effect the heating application values are now also in the lighting application.

The M1 only uses percentages.....not 256 values.

It kind of looks likes this:

Homeseer <-------M1XEP------> M1G <--------C_bus Interface--------> C-Bus Network (lights/thermostats) <-------------> PICED

So for example, if I set a value of 19% (for 19 degrees) in Homeseer the M1 receives the value and coverts it to 048 (using the correct C-bus formula in the NESS interface) and sends it out on the C-bus network. The PICED sees the change in the phantom lighting group and translates it to the heating group, and the thermostat get set to 19. Good.

But if I set the temperature to 19 degrees using the thermostat itself the error occurs. Setting 19 degrees on the thermostat results in PICED seeing the change which translated to 048 the phantom lighting group (as per the C-bus formula). The M1 then sees the change in the lighting group value. But instead of following the correct C-Bus forumla it reports a setpoint of 18 degrees due to the rounding bug in the NESS interface.

Likewise the room temperatures are incorrectly reported. If the thermostat is reporting a room temperature of 22 degrees the M1 reports 21 degrees.

I know this is a minor issue in the scheme of things. But it is surprising how different a room feels between 18 and 19 degrees. Or 20 and 21 for that matter, especially if you live in that space for a while. Humans can actually detect a difference in temperature of around 0.2 degrees.

Of course this also happens for all lighting groups. But that is not important and it is very difficult to tell the difference in brightness between 19 and 20%. It also happens with the audio volumes on the Speakercraft amp but these are not controlled by C-Bus.

It's minor I know. But why NESS just can't simply fix the bug in the firmware is beyond me. Surely it's just a line of code in the firmware.

 

I have given this some thought and might be able to do some trickery in the PICED coding. But this will not fix the lighting or volume problems.

 

If you have a wiser or colour touchscreen you can connect to the M1 via TCP and get the data directly. That's how I do it these days. I put some code in the logic examples a while ago that does it all for you. It only reads data at the moment but writing is quite straightforward.

http://www.cbusforums.com/forums/showthread.php?t=16018i