modbus for modular2_dio10

Revision:
0:998a68b8defc
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed-os.lib	Tue Sep 17 01:59:40 2019 +0000
@@ -0,0 +1,1 @@
+https://github.com/ARMmbed/mbed-os/#1bf6b20df9d3cd5f29f001ffc6f0d0fcbbb96118