FEMS REST API guide

Introduction

To retrieve values, a GET request to the following address has to be sent: http://[IP]:80/rest/channel/[COMPONENT]/[CHANNEL]. You have to replace [IP] with the IP-Adress of the FEMS and [COMPONENT]/[CHANNEL] according to which values you would like to retrieve. For the request to be successful, the Authorization header has to be set with the password "user" and a username of your choice (e.g.: "x").

API values

This is a list of components and their channels that I found interesting. The list is not complete. More (but not all) components and channels can be found in the official documentation here and here. To get every available channel for a component see the example scripts below. To know which components you have simply click on the green tick in the top right corner of the FEMS online monitoring dashboard.

Component	Channels	Notes
`meter0` (grid meter)	`Frequency`	power grid frequency


`battery0` (the first battery)	`Tower0PackVoltage`
	`Tower0NoOfCycles`	number of charging cycles
	`Tower0Module0Cell000Voltage`
	`Tower0TemperaturePreMos`
	`Current`
	`State`	state of this battery (ok, info, warning, fault)
	`Soh`	state of health
	`Soc`	state of charge
	`Capacity`	rated capacity of this battery
	`MaxCellTemperature`
	`MinCellTemperature`
`_sum` (sum of the whole system)	`EssSoc`	state of charge
	`GridMode`
	`EssActivePower`	charging power (negative), discharging power (positive)
	`EssReactivePower`
	`EssActiveChargeEnergy`
	`EssActiveDischargeEnergy`
	`EssCapacity`	rated battery capacity
	`State`	global state of the whole system
	`GridBuyActiveEnergy`	energy consumption from grid
	`GridSellActiveEnergy`	energy sold to grid
	`ProductionActivePower`
	`ConsumptionActivePower`
	`ConsumptionActiveEnergy`
`batteryInverter0` (the first battery inverter)	`AirTemperature`
	`BmsPackTemperature`
	`RadiatorTemperature`
	`WbmsTemperature`
`pvInverter0`	`Current`
	`Voltage`
	`ActiveProductionEnergy`	AC lifetime active energy output

The values from _sum will always return the sum of the whole system, e.g. if you have only one battery, _sum/EssSoc and battery0/Soc will return the same value.

Example: Python

Here is a quick example on how to get the state of charge with python:

import requests

url = "http://192.168.0.0:80/rest/channel/_sum/EssSoc"

username = "x"
password = "user"

session = requests.Session()
session.auth = (username, password)

response = session.get(url)
response.raise_for_status()

print(response.text)

The response will be in the JSON format and could look like this:

{"address": "_sum/EssSoc",
"type": "INTEGER",
"accessMode": "RO",
"text": "Range 0..100",
"unit": "%",
"value": 75}

Multiple values can be retrieved with one request by listing multiple channels like so: url = "http://192.168.0.0:80/rest/channel/battery0/(Tower0PackVoltage|Current|Soh)" Now the response will contain the three requested values Tower0PackVoltage, Current and Soh (state of health). All possible values/channels for a component can be requested by using (.*) as channel: url = "http://192.168.0.0:80/rest/channel/battery0/(.*)" Now we can print all the available addresses:

for entry in response.json():
	print(entry.get("address"))

If you have for example multiple batteries, you can retrieve the same values for every battery with one request by replacing the number in the component name with .+ like this: url = "http://192.168.0.0:80/rest/channel/battery.+/Soc" The URL above can be used to get the state of charge for every battery.

Sources

[1]	FEMS App REST/JSON Lese-/Schreibzugriff :: FENECON Dokumente
[2]	FEMS Glossar :: FENECON Dokumente
[3]	Fenecon Home und das Rest-API