Hi, i have purchased an Eastron SDM630 Modbus RS485 3-phase kwh meter (mid certified) to measure what goes into my electic car. It will be installed right after the 3-phase circuitbraker (eart breaker).
So i need some interface now from the rs485/modbus on the sdm630 to my openhab installation.
When googling around I come across either rs485-USB OR rs485-Ethernet kind of devices. But it remains somewhat unclear to me what is best to use (supported).
What would be the most convenient way to connect this rs485/modbus meter to my OpenHab implementation ? And maybe specifc device suggestions ?
PS - i might add a few more of these modbus meters to measure my heatpunt and solar panel output.
openHAB supports both common varieties of Modbus.
Modbus-TCP talks over ethernet or WiFi.
Modbus-RTU talks over some kind of serial hardware. That’s usually RS-485, but doesn’t have to be.
Obviously, wherever openHAB is hosted you would need a hardware port to allow communications of the type that you have chosen
Most server hosts will have ethernet already.
Some will have serial of some kind.
But for wired RS-485 you almost always need a USB-485 dongle.
Your meter has only wired RS-485.
You’d normally add a USB-485 dongle to your server and a length of cable.
Modbus gateways are available that can interface Modbus-TCP over WiFi or ethernet to Modbus-RTU over wired RS-485.
These are transparent in operation - openHAB would neither know nor care if you used one of those, so there simply is no “support” as such.
Just like a USB-485 dongle, the gateway will drive a serial bus allowing several serial slaves to be connected.
I use the USR brand gateways, but I wouldn’t bother for this purpose, would use a cheap USB dongle.