Unexpected data message start byte when reading ISKRA IEC62056-21 smart meter

I have an ISKRA MT174 smart meter with an optical, IEC62056-21 compatible interface.
For reading the data I have an optical USB-IEC interface (from ELV electronics) which in principle is working. When I install the smartmeter binding (in my dockerized OH3 environment with OH3.0.2 latest), setting mode and baudrate I can see, that data is transmitted to the smart meter and that the smart meter is answering.

cat /dev/ttyUSB1 (inside Docker) gives me the following result:


what shows to me, that data transfer in principle is working.
On the OH3 side I see in the logs

2021-05-07 22:41:14.053 [INFO ] [ding.smartmeter.internal.MeterDevice] - Opening connection to smartmeter:meter:netz
2021-05-07 22:41:25.131 [WARN ] [.iec62056.Iec62056_21SerialConnector] - 1. reading attempt failed: Received unexpected data message start byte: 7F. Retrying /dev/ttyUSB1...
2021-05-07 22:41:25.134 [WARN ] [.iec62056.Iec62056_21SerialConnector] - Delaying retry by PT10S
2021-05-07 22:41:46.196 [WARN ] [.iec62056.Iec62056_21SerialConnector] - 2. reading attempt failed: Received unexpected data message start byte: 7F. Retrying /dev/ttyUSB1...
2021-05-07 22:41:46.197 [WARN ] [.iec62056.Iec62056_21SerialConnector] - Delaying retry by PT10S
2021-05-07 22:41:54.089 [WARN ] [ding.smartmeter.internal.MeterDevice] - Timeout occured for smartmeter:meter:netz; The source did not signal an event for 40000 milliseconds and has been terminated.

repeating all the time.

What I’m doing wrong? Is there any additional configuration I need to do?

Thanks in advance,


Same problem here.
Running OH3.0.2 in a docker on RPI4.
My setup was working very smooth, and smartmeter binding was working perfectly.
But after a while, or maybe after upgrading to 3.0.2, I will get connection time out.

I also checked inside the docker container, I’m able to receive the messages on /dev/ttyUSB0…

Strange behaviour.

I have seen no difference to 3.0.1 version. Did you come any further with this topic?
I’m at the moment stuck here, no further ideas what I can try…

No I did not come any further.
Parallel I opened a issue report on github ([Smartmeter] binding stops working · Issue #10678 · openhab/openhab-addons · GitHub)
Maybe someone will have a look into this.

For the moment i have a workaround using vzlogger (via docker image torstend/vzlogger) and http binding.
This works without any problems!

But it would be perfect, if smartmeter binding would work as well…