scs and keypad comms failures

[slychiu]

If the red D9  is blinking it means the UCM is replying, which also means that it received the correct message from Comfort, so the UCM must be communicating

Start the Bus monitor before the time that it happens. See what it captures when the fault happens

[wexfordman]

[user=1]slychiu[/user] wrote:

If the red D9  is blinking it means the UCM is replying, which also means that it received the correct message from Comfort, so the UCM must be communicating

Start the Bus monitor before the time that it happens. See what it captures when the fault happens

Will do, thanks

[wexfordman]

[user=1]slychiu[/user] wrote:

If the red D9  is blinking it means the UCM is replying, which also means that it received the correct message from Comfort, so the UCM must be communicating

Start the Bus monitor before the time that it happens. See what it captures when the fault happens

Hi Slychui,
Ok, velbus heating relay was on from about 3pm this afernoon and left on all the time. First failure came in at 16:54 as you will see from the event log. I also have the enclosed bus monitor file for the same period, but not clear on how to interpret it. There are corresponding error messages in it at the same time.
Heating relay was turned off at approx 1823pm.
Regards,eamon
bus monitor file was too large, drop box location is here
https://www.dropbox.com/s/6tc1t5fnnt7ea7...2.txt?dl=0

[slychiu]

The problem seems to be the RS485 bus (KA KB) has interference so that the messages are garbled

The NAK replies means that the checksum is wrong in the message

16: 52: 28: 056 ----< 03 53 4E 35 43 02 <--->SN5C               NAK reply from/to Rio/Scs03
16: 52: 28: 072 ----< 03 53 4E 35 43 02 <--->SN5C               NAK reply from/to Rio/Scs03
16: 52: 28: 185 ----< 03 12 4E 39 44 02 <--->N9D               NAK reply from/to Ucm 02
16: 52: 28: 244 ----< 03 12 4E 39 44 02 <--->N9D               NAK reply from/to Ucm 02
16: 52: 28: 306 ----< 03 12 4E 39 44 02 <--->N9D               NAK reply from/to Ucm 02
16: 52: 28: 369 ----< 03 12 4E 39 44 02 <--->N9D               NAK reply from/to Ucm 02
16: 52: 28: 533 ----< 03 51 4E 35 45 02 <--->QN5E               NAK reply from/to Rio/Scs01


after this time, all the messages are NAKs


The switching on of the relay must be causing some sort of interference to the bus

[slychiu]

Did you press the Start Button or the Bus Analyse button?

The Bus analyse button gives the polling and reply information which seems to be missing

[wexfordman]

[user=1]slychiu[/user] wrote:

The problem seems to be the RS485 bus (KA KB) has interference so that the messages are garbled

The NAK replies means that the checksum is wrong in the message

16: 52: 28: 056 ----< 03 53 4E 35 43 02 <--->SN5C               NAK reply from/to Rio/Scs03
16: 52: 28: 072 ----< 03 53 4E 35 43 02 <--->SN5C               NAK reply from/to Rio/Scs03
16: 52: 28: 185 ----< 03 12 4E 39 44 02 <--->N9D               NAK reply from/to Ucm 02
16: 52: 28: 244 ----< 03 12 4E 39 44 02 <--->N9D               NAK reply from/to Ucm 02
16: 52: 28: 306 ----< 03 12 4E 39 44 02 <--->N9D               NAK reply from/to Ucm 02
16: 52: 28: 369 ----< 03 12 4E 39 44 02 <--->N9D               NAK reply from/to Ucm 02
16: 52: 28: 533 ----< 03 51 4E 35 45 02 <--->QN5E               NAK reply from/to Rio/Scs01


after this time, all the messages are NAKs


The switching on of the relay must be causing some sort of interference to the bus

Thanks slychui,
It is odd though is it not that this interference issue comes in at specific times during the day. For example, the relay was turned in for a good hour or more without problems, and the naks just started to come in at that time when nothing had changed, and nothing was done to trigger this interference.

[slychiu]

The intermittent NAKs started at 15:18 in the bus monitor, but became worse until 16:+  when it happens all the time

If you have an oscilloscope you can use it to see what the KA/KB signal looks like

[wexfordman]

Hi Sychui,

No, dont have an oscilloscope unfortunately. I have been wathcin the NAKS over he last 20 mins, and counted 7 of them over that period. That was with the heating relay off.


Is the presence of NAK messages unusual or would you expect a number of them to come in even in a good system ?

Do you think that the vmb4ry is what is introducing the noise at this stage, and if so, how can it cross the velbus onto the comfort bus ?

[slychiu]

NAKs can occur occasionally on the Bus, which may be due to noise and interference.

Your problem seems to be interfence caused by the load switching on. It may or may not be due to Velbus.

Can you disconnect the load and turn it on manually eg using a switch so it is isolated from Velbus. Seee if that causes the same problem

[Ingo]

As a test, I ran my network for most of the night without even one NAK. That Keypad02 of yours looks a bit suspect...

Confirm that you receive NAKs for this device all the time or just when the boiler is On? If it\'s giving these errors all day then perhaps just remove this keypad for a while (as close to Comfort as possible to rule out induced noise in the KP02 cabling). I think in the absence of a clear culprit you need to try the process of elimination.