Support M487 board

Dependencies:   Modbus nvt_rs485

Revision:
0:69a9b661c0ca
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/nvt_rs485.lib	Fri Oct 06 02:28:18 2017 +0000
@@ -0,0 +1,1 @@
+https://mbed.org/users/wclin/code/nvt_rs485/#4c9d65e9275c