profibus

https://kknews.cc/news/ygkyq8k.html

VPN

http://www.jfcarter.net/~jimc/documents/vpn-setup-1501.html

baudrate 算法

單位bit傳送時間 = 1/9600bps = 1.041×10^-4（秒）
1Byte傳送時間 = 1.041×10^-4×10_bit = 1.041×10^-3（秒）
（1Start Bit + 8Data Bits + 1Stop Bit = 10bits）

Yocto 使用之技巧

https://www.kancloud.cn/digest/yocto/138624

subnet

http://www.subnet-calculator.com

rfkill

https://askubuntu.com/questions/98702/how-to-unblock-something-listed-in-rfkill

MQTT

http://www.xappsoftware.com/wordpress/2014/10/30/install-mosquitto-on-mac-os-x/
https://www.jianshu.com/p/a356fd3340f3