How can the host application identify the protocol firmware variant and version?
Which protocol stack firmware is running on netX 90 COM side, PROFINET, EtherCAT, EthernetIP, ...?

There are 2 sources of information

1. DPM mailbox packet "HIL_FIRMWARE_IDENTIFY_REQ"
   This packet is documented in the manual Packet-based services (netX 90/4000/4100), chapter "Identifying Channel Firmware"
   
   
2. The "Channel Information Block" of the DPM System Channel
   This data structure is documented in the manual Dual-port memory interface, chapter "Channel Information Block"

HIL_FIRMWARE_IDENTIFY_REQ

Channel Information Block