freemodbus收藏学习网址
https://www.cnblogs.com/axinno1/p/8521481.html
https://blog.csdn.net/xukai871105/article/details/21652287
freemodbus modbus TCP 学习笔记
freemodbus modbus TCP 学习笔记
https://www.cnblogs.com/magic2008/p/6572778.html
freemodbus移植讲解 ZZ
https://www.cnblogs.com/luomingui/archive/2013/06/14/Modbus.html
Modbus通讯协议学习 - 认识篇
https://blog.csdn.net/xukai871105/article/details/16368615
MODBUS协议整理——汇总
https://blog.csdn.net/xukai871105/article/details/17471865