> I'm not able to find documentation what is purpose of the RPC? Could someone give any indicators how I can start debug this behavior? Or there is some documentation about the RPC?

The RPC system allows midas clients to issue commands to each other. In the case of the VX2740 code we use it so the midas webserver (mhttpd) can tell the frontend to perform some actions when a user clicks a button on a webpage.

I've been writing most of the code for the VX2740 for Darkside, so will contact you directly to help debug the issue.