Can we connect an external UART-TX to pin RX2 of ArdusimpleB2 in order sending own telegrams to XBee Wifi? According to documentation this is also connected to TX of ZED-F9P. Would two TX collide then or is there logic to seperate, i.e. avoid destroying the ports? (schematics are seemingly not available to check on ourself)
Yes it is possible, this is one of the intended use cases of the board. In this case, make sure that ZED-F9P UART2 is configured to Protocol out = NONE.