User manual

mission takes some time. However, the frequency at which new data are transmit-
ted is so high that the PC will be bombarded with messages.
TCP CLIENT
The last chapter was about the UDP, which can be used to send and receive data
easily. The protocol already permits implementing a large number of applications.
In this chapter, we will deal with the TCP (Transmission Control Protocol). The
module will take the role of the TCP client in this chapter. This is the role that your
PC at home has towards the web server. The difference between TCP and UDP
can be generally summarised as follows:
U
The connection is only between precisely two devices.
U
The packages sent are reviewed for transmission errors and
corrected if necessary.
U
TCP is used especially online.
U
The protocol is slightly slower than UDP, but also safer.
The protocol is used by your PC and a web server from which you want to load a
website to connect the two parties. The actual website content will then be trans-
mitted in HTTP format (HyperText Transfer Protocol). How this works will be ex-
plained in the following chapter.
3.1 | A browser
This experiment uses the existing setup again. It is about getting to know the basic
structures of TCP communication with the serial monitor.
The program
The program's function is similar to the SoftwareSerial-
program of the first experiment, but among others, it connects to the WLAN inde-
pendently at start-up. This saves you a lot of typing and you can start more
quickly. Do not forgot that you need to enter your home network’s data into the
program. Then enter the following command line in the serial monitor:
AT+CIPSTART="TCP","www.example.com",80