oh, sorry, all tcp-clients could send a command, and the µC answers and ALL tcp-clients get them. so all tcp-clients are on the same state.
the risk of simultaneously send from tcp-clients is nearly zero or if greater zero it's not the biggest problem.
first of all i want to have a stable conncetion, both tcp and serial, than i could (maybe) built in some restrictions for the µC.
thanks in advice