MTN6500-0103 IP Router KNX Communication Issue

[ErkinV]

Hello everyone, I have a question and wanted to illustrate it with a drawing to explain it better.

As shown in the first image, I have a line with an IP router and 63 devices connected underneath. The addressing on this line is also configured accordingly. Since we were experiencing some telegram transmission issues, we added a new-generation router in between, as shown in the second image.

However, when we connect the CAT-6 communication cable, the KNX LED on the field device starts flashing red continuously, and none of the devices on the line become reachable. it essentially locks the entire line. Interestingly, when I disconnect the building's switch and instead plug in a CAT-6 cable from my own computer, the issue disappears completely. You can also see this behavior in the videos.

Here are my questions:

- Other than the address of the newly added device, all the devices connected underneath still have the same addresses. Could this cause a problem?

- Is there a security feature on the new device that we are unaware of and need to activate?

We need to urgently get back to our client regarding this issue, so I would really appreciate your support.

Thanks in advance to everyone!

@Thomas_Rohde

@Erwin-vd-Zwart 

@Heribert_Dölger 

[Heribert_Dölger]

Hello ErkinV

You cannot implement an IP router in the subline of another router or coupler, and especially not with an address that does not match to this line. Question would be whether the devices in the subline of IP router 5.1.0 are still connected as well to line with router 1.10.0.

IP Routers should share the same main line, in this case the IP Line. The addresses of the Routers should be in the same Domain. So if the first one is 1.10.0 the other one could be 1.11.0. But then all devices connected to router 1.11.0 must have addresses from 1.11.1 … 1.11.63. And of Course there no direct bus Connection between both lines and you would Need another KNX power supply for line 11.1.

In General, I think this solution approach is not the best. As you Mention communication Problems it would be better to analyse why those communication Problems appear. If it is a matter of wiring length or insufficient power supply it would be better to install a coupler in the middle of line 1.10 and configure it as a repeater (with address 1.10.64). The other devices in this line then could Keep their address. But you would then need an additional KNX power supply for this new Segment.

Is the shown line the complete network or are there additional lines in the Project? If this is the whole network you would not Need a router at all, maybe only the interface function to get Access to the network from ETS.

The blinking of KNX LED at the router indiates Transmission Errors but could be minor Errors like missing acknowledgements or repeat telegrams. I Guess the blinking stops because with ETS connected the acknowledgements will come from ETS.

[ErkinV]

Hi Heribert,

In the first screenshot from ETS, you can see the topology. I marked the split line in red, and the newly added router on that line is marked in green. In the second screenshot, the devices from the red line are physically connected in the field to the newly added router (the green line).

What I would like to ask is: should I move the devices in the red area (from the second screenshot) under the new router with the address 5.1.0, and also update their addresses accordingly? Is this the correct approach?

[Cristiano_Carli_Ballola]

Hello ErkinV,

Regardless of where the devices are currently installed or will be moved, what you absolutely need to do is change the parameters of the IP routers by setting filtering according to the filter tables calculated by ETS.
If you leave the communication on "Route", all telegrams of the whole project, which appears to be quite large, will pass through each line, causing a huge traffic communication, which could be the cause of the issues you complain about.

[ErkinV]

Hi Cristiano,

I'm asking to clarify something I'm not sure about — you're suggesting that it would be better to set all the attached configurations to "filter," right? I also have different routers used in this project. If I change them all to "filter," would it help ease the data traffic? As you mentioned, apart from the issue in the subject line, I'm also experiencing some lags in data traffic as you described.

[Cristiano_Carli_Ballola]

Yes sir!
It's more than suggested, it's mandatory.
This is the main purpose of any KNX coupler, handle the telegrams traffic within the line they belong to.
They are equipped with the so called filter table, in which are inserted all the group address telegrams that need to be forwarded through their designated KNX bus line.
The filter table is automatically generated by ETS according to your project configuration.
Bypassing the filter table means, for most telegrams, tripling traffic!

[ErkinV]

Hi Cristiano,

As indicated, I have arranged the addresses according to the device topology and sorted them based on the IP Router. I also configured all the routers with the filter settings and uploaded the configurations.

However, when I connected the CAT data cable of this new device to the system backbone and tested it, I experienced issues with the other data: devices stopped working and there were disruptions in the scenarios.

Is there another approach or test I should try to solve this issue? I also added an additional power supply to the router to prevent bus voltage drops, but I still encountered problems in the system.

Please find the addresses attached. 😞

[Cristiano_Carli_Ballola]

Hi @ErkinV ,

using ETS you are you able to monitor and record the data traffic within the KNX Bus line and the KNX IP line.
By analyzing the recording you should be able to verify if the telegrams are routed correctly between different lines and/or areas.
The communication on KNX/IP takes place in Multicast mode; check with the support of the IT manager that the switches/routers of the network infrastructure have been set up correctly for this to happen

[ErkinV]

Hi Cristiano,
I spoke with someone from IT, but they keep insisting that everything looks fine when they check it. How can I prove otherwise? How can I perform the task you mentioned in the program?
Would it be possible for you to explain it to me, perhaps with an image or a video?

[ErkinV]

"Hi, could you please help me with this matter?"

@Thomas_Rohde

[Thomas_Rohde]

Hello ErkinV!
If I would be in your shoes, I would try to seperate (if somehow possible) the complete KNX IP-Network from the given IT-Installation.

Just for a test.

Means to use a simple router/switch which you trust and where you have good experience with.
If the installation is then working properly as you expect, I would ask the IT guys why is it working within your local test setup but not at all in the real installation.

I guess they have a manageable router/switch which is somehow blocking parts.