Hi,
I have just installed a BYD battery pack onto my off grid system, replacing my ageing Lead Acid batteries. I have run into an issue with monitoring using the MQTT capability of the Venus GX.
Once the BYD battery is connected, the Venus creates a number of new MQTT topics - these include quite a few indicating fault conditions and one called "Connected" (in my case its full topic path is N/9884e3aed7f6/battery/512/Connected).
This topic delivers a payload of {"value": 1} - which is a valid JSON formatted string - great.
However, if the RS485 cable between the venus and the BYD BMS is interrupted, you would expect this value to report {"value": 0} - sadly it does not. The payload becomes NULL (ie nothing) and this is NOT valid JSON. This causes the JSON decoder (at the subscriber end) to throw en exception and causing my alerts to fail.
If values are going to be sent using JSON encoding, ALL values should be JSON encoded.
I have no way of simulating the other fault topics so I can not say if they do the same.