“in datasheet of AD-FMCJESDADC1-EBZ there’s a information that external trigger
can be used. However there’s no information how it works and how to use it.”
The connects board mentioned above with KC705 (Kintex-7 board).
The trigger is routed to the FPGA (EXT_TRIGGER_P/N on G2/G3).
IIRC, it comes in single ended. The actual FPGA pins depends on the carrier.