Support M487 board

Dependencies:   Modbus nvt_rs485

Revision:
0:69a9b661c0ca
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed_app.json	Fri Oct 06 02:28:18 2017 +0000
@@ -0,0 +1,5 @@
+{
+    "config": {
+        "def-rs485-port": "1"
+    }
+}