how to know if a connection uses https wireshark

OK, in that case everything seems much simpler. If there is no tcp stack available for the PLC (possibly due to memory limit or due to complete absence of IP stack, you haven't told us about what the PLC can do at network level), you may need an intermediate box which would understand the protocols which the PLCs already can talk and would act as a mediation gateway to the TCP (or even IP) world, translating the queries in PLC's native protocol to queries to Mongo transported using TCP, and vice versa. That once again leads us to need to have a working tcp stack on the PLC, as without it, you'll simply not be able to send your application queries and receive the answers. So once a tcp session is established (which from the application point of view is equal to successful opening of a socket), you can write your query to the socket, and read back from it the answer, without worrying about reliability of the transmission, because the tcp transport below does that for you. The way that there is no (need for) connection handshake at application level (the query/answer format/protocol used to talk to the database), because tcp is a reliable transport in terms that it itself takes care about retransmission of eventual lost packets, delivering the bytes of the messages in proper sequence in case that the packets' order swaps in transmission etc. Clients should connect to the database with a regular TCP/IP socket.

How to know if a connection uses https wireshark