DALI gateway turns on all the lights randomly

[joseloureiro]

Hi,

I'm currently working on a project with a couple dozen DALI Gateways (MTN6725-0004). Some of the gateways randomly turn on every light on both channels. At the moment I detected this issue in 3 gateways but there might be more.

I left a laptop on site recording the KNX network traffic overnight and searched for the moment any DALI gateway would send a status value telegraam of 100% on all their groups. I found out that there's no telegraam sent by any device that would trigger this behaviour.

This behaviour is exacly the same as to what would happen if the gateways were powered off because every group is configured with "Value on DALI Power Fail: 100%". But I don't think the gateways are losing power as they are all connected to the same UPS.

How can I troubleshoot this problem?

PS: Telegraam written wrong because somehow the word is not permitted in this community

[Heribert_Dölger · Accepted solution]

Hello Joseloureiro

Difficult to say why this is happening.

I assume that the ECGs indeed go to DALI power failure mode.

A DALI power failure could happen due to
- loose contact in the DALI wiring
- defective ECG
- DALI line is overloaded (the gateway will switch off the DALI power when there is more than 250mA current on the line (but normally should not happen as an ECG is only allowed to have a consumption of 2mA))

All the above mentioned possible reasons are related to the dedicated DALI line. As you are using 2-channel DALI gateway it is not very likely that the same incident occurs on both DALI lines at the same time. But maybe you should double check if it really happens on both DALI lines at the same time.

Another possible reason might be that when switching from mains power to UPS there is a short delay until the UPS power is available and the gateway then is not powered for a few seconds. This could be enough that the gateway stops providing DALI power and due to that the ECGs go to 100%.

Another point to check is settings of the behaviour at KNX power failure and recovery (in case the KNX power supply is not buffered by UPS). In case of KNX power failure and recovery the gateway might send values to the ECGs depending on the settings in ETS. Best setting might be to select "set to last value".

To come closer to the root cause you might monitor the communication on the DALI line. For that you would need DALI monitor software (like Tridonic masterCONFIGURATOR which is free of charge) and a DALI interface to connect the PC to the DALI line. If no command is sent by the gateway in failure case then it is clearly a behaviour executed by the ECG itself. If there is commands coming from the gateway we need to check why the gateway is sending such commands.

You might also make different failure settings for line 1 and line 2 in one gateway and check if the result is same or different. Or you configure two gateways with different settings on power failure and see if there is a difference or not.