Question about getting response from device

[p0tvin29]

I have a lock system hooked up to the tcp controller i'm using with node-modbus. I can successfully send the unlock to modbus but I'm trying to figure out a way to listen to the device. After unlocking, when the device LOCKS how do I listen on port 502 so that I can trigger an event?

My current code is:

modbus.tcp.connect(502, "10.100.55.17", { debug: "automaton-2454" }, (err, connection) => {
    //do something with connection
		connection.writeSingleCoil({ address: 0, value: 0 }, (err, info) => {
        console.log("response", info.response);
    });

		connection.writeSingleCoil({ address: 0, value: 1 }, (err, info) => {
        console.log("response", info.response);
    });

		connection.on("read-coils", (request, reply) => {
				console.log("**READ-COILS**")
				reply(null, [ 0, 0, 0, 0, 0, 0, 0, 0 ]);
		});

		connection.on("write-single-coil", (request, reply) => {
				console.log("**WRITE-SINGLE-COIL**")
				reply(null, 0, 1);
		});
});


modbus.tcp.server({ debug: "server" }, (connection) => {
    // do something with connection

		connection.on("read-coils", (request, reply) => {
				console.log("**READ-COILS**")
				//reply(null, [ 0, 0, 0, 0, 0, 0, 0, 0 ]);
		});

		connection.on("write-single-coil", (request, reply) => {
				console.log("**WRITE-SINGLE-COIL**")
				//reply(null, 0, 1);
		});

		connection.on("read-single-coil", (request, reply) => {
				console.log("**READ-SINGLE-COIL**")
				reply(null, 0, 1);
		});

		connection.readCoils({ address: 0, quantity: 16 }, (err, info) => {
        console.log("response", info.response);
    });

		connection.readCoils({ from: 0, to: 7 }, (err, info) => {
        console.log("PDU", info.pdu);
        console.log("response", info.response.data);
    });

}).listen(502, () => {
    // ready
		console.log("** GOT RESPONSE FROM DEVICE **")

});