How to communicate with server (Nano10)

[kirk-wgt]

Apologies for any dumb questions; I'm new to this.

We've got a Nano10 connected to a few devices via RS485.  Across the internet, I've got a server application that needs to:
- Know when certain inputs on the Nano10 have changed
- Tell the Nano10 to set/clear certain outputs

Let's assume that routing & firewalls are figured out so that both the Nano10 and Server are able to reach each other.

In a perfect world, I would keep a permanent socket connection between the device and my Server application, where I could easily peek, poke, poll, etc.
Is that possible?  If yes, what protocol/technique do I use for this?  FWIW I prefer a device-initiated connection but Server-initiated also works.

If this model doesn't fit how the Nano10 ideally operates, then what's the next-best technique to accomplish my goal with minimal latency or connection hassles?

[garysdickinson]

The Nano-10 has built in support as a slave device via Modbus TCP/IP.  This is an industry standard communication protocol.  A server can access the PLCs, INPUTs, OUTPUTS, RELAYS, DM[], DM32[] and several other PLC internals.

This is how most HMI devices interact with PLCs.  This is how remote data logging is done with PLCs.

Modbus TCP/IP requires little or no software support in the .pc6 program for the Nano. If your server can act as a Modbus TCP/IP server then most of the programming is on the server end.

This is not the only approach that you can use, but it is my favorite. 

Gary Dickinson