Use REST API for getting second-by-second data

1

Hello,
I would like to measure cell data with resolution per second in a FENECON Commercial battery system. Is that frequency possible with the limitations of the REST API?

Thanks for information!

2

should not be a problem, because the rest-api is also fired every-second. if the performance and the load will be good enough you have to check out. to get every second data, you can use sockets with less overhead.

best regards

pauli

3

Thanks for the answer @p.wimmer. What exactly do you mean by “sockets with less overhead”?

4

a socket connection has less overhead than x rest calls and is so much faster and you get immediatelly all changes over the socket-connection

5

I was told that not all signals are accessible publicly via Modbus TCP and that cell data is only extractable via REST API. Is that not true?

6

Hi @JBrucksch and welcome to the OpenEMS Community.

I assume with “socket-connection” Paul refers to the (undocumented) API provided by the “Controller API Websocket” (https://github.com/OpenEMS/openems/tree/develop/io.openems.edge.controller.api.websocket).

This is the API that is used by the local OpenEMS UI to receive real-time data from an OpenEMS Edge. If you want to dig further, this code block can give you a starting point: https://github.com/OpenEMS/openems/blob/develop/ui/src/app/shared/edge/edge.ts#L178-L204

If you were running your own OpenEMS, you could of course either use

Both variants are unfortunately not available with FEMS at the time of writing.

Regards,
Stefan