DALI ECG Power Recovery Problem

[joseloureiro]

Hi,

I'm having a problem with the ECG power recovery function on a MTN6725-0004 DALI Gateway. In our site the DALI Gateways are powered by an UPS. I selected the option Last Value for ECG power recovery but it just isnt working that way. If I have all the lights turned on, when I trip the ECG breakers and turn it back on, some of the lights turn back on, others not. If I do the other way around and turn off all the lights before I trip the breakers, same thing happens, I turn it back on, some of the lights turn on, others not. This is very weird because the behaviour is the same.

I'm not sure if this might be related with the type of ECG installed in this section of the building as in other areas of the building the ECGs assume the last value on ECG power recovery. Both areas have the following settings:

Any idea of what might be happening?

[Heribert_Dölger · Accepted solution]

Hello

Some background information why you see this behaviour:

The DALI gateway permanently monitors the status of all ECGs. Depending on the number of connected ECGs this process can take up to 2 min to check all ECGs.

Example: During a 45sec power cut in your installation the DALI gateway will have detected some of the connected ECGs as no longer present but not yet the others. If an ECG is detected as present again the DALI gateway will send its last value to the ECG. But this will only happen for the ECGs that before were detected as "missing". Not for the others. This is why you see "strange" behaviour that after power return some ECGs are on and others are off.

[joseloureiro]

Hi,

Thank you for your reply.

I'm a bit confused. I saw the post titled "Powering DALI gateway" and the problem is indeed similar. But from my understanding if I use the setting last value, even if the ECG power cut is less then 2 minutes it shouldn't really matter, right?

Regarding the ECGs that the DALI gateway detects as not present, once they power up again the gateway will tell them they should assume the last value before the power cut.

While the ECGs that the Gateway thinks are still present shouldn't change value at all. When power comes back they should also assume the value they had before the power cut, right? Or do they need the gateway to resend the value?

[Heribert_Dölger]

Hello again

Your expectation indeed is correct: after power recovery the ECG should go to the configured value. The ETS parameter that you can set in the DALI gateway configuration is written into the ECG and the ECG has to adopt this value after power recovery.

As it is not the case in your installation it seems either the ECG is not supporting it or the value was not properly written into the ECG during DALI Download process. According DALI specification the ECG must support this feature. In the initial DALI specification only fixed values were specified ("last value" was not possible). But the DALI specification had been changed about 10 years ago and the feature "last value" is part of the DALI specs since then and every ECG has to support it. If the ECG doesn't support this you should contact the manufacturer of the ECGs.

If the value has not been properly written into the ECG you might try to repeat "download to DALI" in the DCA. But you will need to do a modification in the settings otherwise the gateway won't write the values to the ECGs.

The behaviour at power recovery has to be managed by the ECG. The DALI gateway doesn't "know" about the mains power failure of the ECGs until the monitor process has been finalised for the whole DALI line (the mentioned 2 minutes). Due to that the gateway will only re-write the last value if it has detected the ECG as "missing".