使用函数（ANSI C）更改结构及其成员包含的地址

[EDIT]I added all my main code and some of the external functions used by this code. The code is quite long, but in summary it sends a message to a device measuring some parameters of the water in a container, and the device responds with the corresponding value measured by the sensor. After that the code uses this value to modify the level and temperature of water. Prints the current status of the container and makes a log.txt file.[/Edit][EDIT]I added all my main code and some of the