"Stephen Early" wrote in message
...
In article ,
ARW wrote:
It's a basic set up repeated three times (ie one dimer controlling two
lights).

I assume these are all completely separate, i.e. the control wires
aren't shared between them?

An Osram DALI MCU is "controlling" two lights that are both fed from a
iDrive Quattro CCL driver.

You can power up for the first time and both lights dim nicely together,
then after some time (say 5 minutes) one of the lights just turns on to
full brightness or both lights turn on to full brightness. The dimmer
and power to the lights has not been touched.

It sounds like the lights are going into "system failure" mode - when
the control signal is missing for more than 450ms they change to the
pre-programmed "system failure" output level, which by default is
100%.

Is this affecting all three installations, or just one of them?

The way DALI works is that there's a current-limited power supply to
the control lines, providing between 12v and 20.5v with up to 250mA
available. The various parts of the system communicate digitally by
modulating their current draw from the DALI control lines to drop the
voltage; all DALI system components can sink at least 250mA from the
control lines. A voltage between 9.5v and 22.5v on the control lines
is interpreted as "high level" and anything below 6.5v is interpreted
as "low level".

If the voltage on the control lines at the driver drops below 6.5v for
more than 450ms at a time, the driver will go into system failure
mode.

How have you wired the systems? What size conductors have you used
for the control signals, and how long are they? The usual
recommendation for DALI is 1.5mm^2, going up to 2.5mm^2 for
particularly large systems or long cable runs. What's the voltage on
the control lines at the driver when the dimmer is not being touched?
How about at the dimmer?

I assume you are using the DALI power supply built into the Osram DALI
MCU (i.e. you're supplying 230v to the L and N connections on it)? If
not, where is the control line power supply coming from?

You need to wait for Dave, he'll know.