I wrote 2 classes to handle Nuflo and Troll brand RS-485 sensors (dependent on a ModbusMaster library) and I could possibly convert these into public libraries if there was any serious demand for it.
Note these sensors use proprietary modbus protocols, so it will probably be useless if you use a sensor from a different brand (e.g. text encoding, 32 bits number reading, etc…). The code I wrote was heavily tested on these devices, but it may not work properly with other devices, and I won’t be able to troubleshoot your own particular device.
I would be interested in knowing what you developed those for?
We do a lot of work with other types of flowmeters, such McCrometer for Agriculture. We also sell an Electron based product that has modbus integrated.
Can’t give you too much detail, because I don’t really know the final client, yet they seem quite sensitive with regard to security.
Mostly the flow and level meters are used with water, the electron polls, aggregates and forward the data from both type of sensors, which ends in a DB.
We recently added a nice 1.5" display to the device, looks pretty good.