1、The hardware connection
If the TX port on the device that sends data (data blocks away) terminals, with the RX port on the device that receives data (data access block) terminal, the device A and device B connected between the serial as shown below.
If the serial connection is also seen as a two-port device and two port terminals to do this mark, the two devices connected via the green box for serial communication connections as shown below.
If radio serial cable replacement, the device A and device B communications link between the following figure.
Contrast the above three can be seen, if the composition of the two radio stations as the wireless channel is also a two-port device, the device A and device B, the serial communication cable connection and wireless connection terminals corresponding to the relationship is the same.
2、With a wired connection at different points
Replace wired connections with wireless channel after the communication program to connect with the wired communication program under the same preparation, but there are two differences to note. In the note the following points based on the use of radio, when we can put a system composed of two radio stations is seen as a transparent connection.
Different point 1:
Wired serial communication program in frame format, data rate can be set. Cable itself, these two parameters without any restrictions. Of the radio serial frame format, data rate to be set, and consistent with the connected terminal equipment.
2 Different points:
Wired connection is full duplex serial communication.
Radio communication is half duplex. That radio stations can not transmit data, receive data, receive data radio can not transmit data. Therefore, the transceiver in the communications program should be staggered in time.
General data acquisition and control procedures for sending and receiving time of communication are staggered.
3 Multipoint connection
Automation and control systems usually use multi-point communication, multipoint communication in the way if one uses a cable to connect all the devices connected to the communication from the bus. Connection diagram is as follows:
If the alternative to wired connection using radio diagram below, all the equipment from the equipment and the connection between the master and bus connections are wired the same relationship.
