Proxon T300 Water Heater / Modbus / Hi/Lo Word

Hardware
1

Hi,

I have a Proxon/Zimmermann T300 Water Heater connected via Modbus.

There is a legionalla-function which heats to 70°C every week when enabled. There are registers 59 and 60 counting the seconds when this happened last.

    - name: "T300 Legionellenfunktion Zähler"
      unique_id: t300_legionellenfunkt_zaehler
      slave: 20
      address: 59
      input_type: input
      scale: 1
      precision: 0
      data_type: uint32
      swap: word
      device_class: duration
      state_class: measurement
      unit_of_measurement: s

It works, but the readings don’t make sense: after about 24 hours ist should read ca. 24 * 60 * 60 = 86400 seconds, Hi should be 1 (2^16) and Lo 20864. But I get 11 and 6887 (8.3 days approx.)

What am I missing here?

When I’m done and everything works, I will share my setup here.

Regards,
Heiko

2

Read the protocol sheet of your device. Adjust data_type and swap according to that.

3

The spec says uint16 for both registers, so is uint32 wrong?

4

Quite likely, without swap.

5

When I don’t use swap, the values get even weirder.

The calculation in HA is correct, 2^16 * Hi + Lo, as delivered by modbus.

The question is, how to interpret (and convert) it to the real time

6

Try if it’s counting 0.1s units, that comes more close to the numbers you posted…

I don’t know what you mean now…

7

Thats right, perhaps the documentation I got is wrong here

8

It is! I monitored just the Low-“Word” and it jumps to Zero after about 7100 Seconds (7168 = 1024 * 8 maybe?)

So the documentation is wrong here, I am not yet finished with my integration, when done, I will share it here.