CBus-DALI gateway status correction problem

How old is the unit?

If its a recent purchase (ie i about the last 4 years) there should be no issues at all.

 

Darryl Mc is correct.

The C-Bus / DALI Gateway does not understand the programming of groups into ballasts (and nor can it, without a vast amount of s/w and pain).

Status correction in DALI land merely runs a check of the ballasts to see if their setting is the same as the C-Bus side thinks it should be.

This is just like the means used by C-Bus dimmers and relays with MMIs and status checking + correction, but applied on the DALI side.

The major use for this is 2-fold:

1. In the even of a DALI communication error, the load will (eventually) end up where it should be.

2. In the event that you use something like a DALI switch to control a load, then if you want C-Bus to be the control point master, the switch will be overridden. [Bizarre though it sounds there are sometimes cases where you want this to happen.]

In regards to case 1, DALI has no error checking or confirmation of transmissions, so the chances of a DALI communication failing are real, even though small.

 

If status correction is enabled, then within 1..2 minutes, ballasts should be turned off.

The input units will not be changed.

 

There's no fault with the DALI gateway.

In DALI, group membership lives in the ballasts. This is opposite to C-Bus.

In DALI, a ballast can be set up to have nonsense mappings.

Heres an example:

Ballast A1: In groups G1, G2, G3

Ballast A2: In Groups G1, G2

Ballast A3: In groups G1, G3, G4

NOW... I can control each ballast (through short addresses A1, A2, A3, etc).

If I issue a command to G1, we will see A1, A2, A3 respond as expected.

Now, suppose I issue a command to G3. We'll see A1 and A3 respond.

Or more complex:

I can control G1, and get response from A1, A2, A3.

Then I can turn off A1 ALONE. Whats the setting for G1?

In C-Bus such nonsense just can't happen. You only control groups. In DALI, you control loads, or groups, or scenes, or everything. Now the trouble is that the idea of the level or state OF A DALI GROUP is a meaningless concept, because the moment you do something which violates the ENTIRETY of that group, the concept of the group no longer exists.

So, if you map a C-Bus group -> DALI group, things will work fine UNTIL you control an individual DALI load.

The C-Bus Gateway has NO IDEA of the (DALI side) group memberships of the ballasts. So it cant know and does not know when you have made a change that busted a DALI group and made the DALI group "disappear" as a concept.

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Status correction (as I posted earlier) is a part of the DALI gateway which does this:

- it makes a list of the incoming C-Bus groups
- for each incoming C-Bus Group, it records the last known level of that group
- it keeps that record up to date
(all the above is a memory model of the C-Bus Group state, and it lives in the DALI gateway)
- The gateway visits each ballast BY SHORT ADDRESS ONLY
- The gateway gets the current dimming level from the ballast: "Hey Short Address X, whats your level"
- The gateway compares the ballast view of the level to the C-Bus view of what the level (as mapped from a C-Bus group to DALI Short Address)
- If the levels differ a counter is incremented; if the levels are the same the counter is reset to 0
- If after the comparison of levels, and increment of counter, that counter reaches a value of (I think) 3, then the C-Bus level is used as the "correct" level and that level is transmitted, over DALI, to the errant ballast to correct it.

This is used as a means of forcing C-Bus group levels to always be treated as god-like, and override any errors that might have appeared in the DALI setting of a level. Or screw-ups that come from use of CBus groups mapped to DALI groups with nonsense memberships.

There is NO REFLECTION OF A CORRECTION MADE IN DALI BACK INTO C-BUS.