A tag map, verified before it is trusted
A tag map names each machine's OPC UA tags and what they mean: the state word and how it reads as running, down or planned stop; the counters that book production; the process values; the setpoints that may be written and their bounds. Engineering fills in a worksheet, the CLI turns it into the map, and opc-verify proves it against the live server before a single booking is made.
Kepware and any OPC UA server work today. Ignition through its OPC UA server. Modbus and other protocols reach the MES through whatever already publishes them as OPC UA; a native driver is a module someone has yet to write, and the contract for it exists.
fsmes opc-browse # what the server actually exposes
fsmes make-tag-map # from Engineering's worksheet
fsmes opc-verify # prove the map, tag by tag
fsmes seed-line # create the equipment it describes