christiangurk avatar image
christiangurk asked

Possibility to change EM540 modbus driver to read consuption with higher resolution

I just found out, that the modbus RTU (RS485) driver for the EM540 energy meter in the current venus OS 3.00~14 is reading the register address 0x0034 (kWh (+) TOT) with the length of 4 bytes (INT32) as the total energy (Value weight: kWh*10). The resolution is 0.1kWh. This seems to be a small resolution for small households as for example the hourly consumption is around 0.2-0.3 kWh. So in the VRM portal the statistic is relative coarse...

My suggestion is not to read register 0x0034 but 0x5000 with 8 bytes length (INT64) as the total energy (Value weight: Wh) instead. This would give a resolution of 0.001kWh and would be much more accurate.

I got these information from the Carlo Gavazzi EM540 communication protocol PDF available from the internet. Could that change be implemented in future versions?

And as the duty cycle for the rs485 bus with 9600baud is quite high for the high speed update rate of the EM540, would it be a possibility to add a higher baud rate option? E.g. 57600 baud?

Venus OSEnergy Meterrs485
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1 Answer
maurice-klein avatar image
maurice-klein answered ·

Hello, I agree that would be great.
I have the same problem with that resolution and also a higher refresh rate would maybe speed up the ESS regulation.

Did you find any solution to that?

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christiangurk avatar image christiangurk commented ·
Sorry, no solution for me for now...
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Related Resources

Victron Venus OS Open Source intro page

Venus OS GitHub (please do not post to this)

Energy Meter Selection Guide

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