Design and implementation of RS232 multi-serial channel single-fiber optical terminal

Foreword:

In order to effectively extend the data transmission distance and solve the problems of electromagnetic radiation, electromagnetic interference prevention, non-common ground between point-to-point devices, lightning strike resistance and channel resource sharing when transmitting data through cables, the multi-protocol serial communication controller Intel82530 and single-fiber bidirectional TTL are used. The integrated optical transceiver module is designed with a multi-serial channel single-fiber optical terminal. In the design, the best balance between hardware and software scale was sought. Analyze the causes of communication errors and select a suitable crystal oscillator through calculation to control the communication errors of multi-serial channel single-fiber optical terminals, and obtain accurate baud rates for commonly used communication rates. Multi-serial channel single-fiber optical terminals can be widely used for point-to-point connections using single-core optical fibers to transmit serial data to remote locations. It overcomes the disadvantages of cable transmission of data, improves data reliability, and also reduces the cost of nonferrous metals. Consumption of metal and channel resources.

After years of development and continuous improvement, computer and communication technology have become increasingly mature. With the widespread application of network technology in many fields, more and more information needs to be transferred between various systems safely, reliably and at high speed. The emergence of optical fiber communication technology has broken the shackles of cables and made data more secure, reliable, and high-speed long-distance transmission a reality. Moreover, once optical fiber communication came out, it has attracted people’s favor due to its unique characteristics such as reliable transmission, no electromagnetic leakage, no electromagnetic interference, high speed, and low price. The development of optical fiber communication technology is in the ascendant. The combination of optical fiber communication technology and mature serial communication technology has injected new vitality into the application of serial communication technology. In the 1980s, Intel introduced the Intel82530 serial communication controller, which is a very mature serial communication controller. Because of its many advantages such as reasonable design, stable and reliable performance, high cost performance, and simple interface circuit with microprocessor, it has always been loved by the majority of communication interface hardware designers. This article gives a design example of a multi-serial channel single-fiber optical terminal with five serial channels based on three Intel82530 serial communication controllers and a single-fiber bidirectional TTL optical transceiver module, as well as software design ideas and processes.

1 Working principle of multi-serial channel single-fiber optical terminal When transmitting data in point-to-point communication mode, when the distance is long, a dedicated voice line and a pair of modems are usually needed to connect two computers; when the distance is short, NULL is used MODEM cable to connect. Because the cable has capacitive reactance characteristics, it plays a smooth filtering role in the transmitted digital signals. The farther the distance, the higher the rate, and the greater the impact of capacitive reactance on the data waveform. This will cause distortion of the data waveform, and in severe cases may lead to data transmission failure. In order to ensure effective data transmission, a trade-off must be made between distance and speed. The higher the rate, the closer the transmission distance; the lower the rate, the farther the transmission distance.

When transmitting serial data using a multi-serial channel single-fiber optical terminal, the data transmission distance can be effectively increased without affecting the data transmission rate. Its distance limit is the limit of optical fiber transmission. At the same time, it better solves the problems of electromagnetic radiation, anti-electromagnetic interference, non-shared ground between point-to-point devices, and lightning resistance when transmitting data through cables. Multiple serial channels share one optical core for transmission, which improves data reliability, reduces the amount of equipment, and reduces the consumption of non-ferrous metals and channel resources.

The working principle of the multi-serial channel single-fiber optical terminal is shown in Figure 1. The multi-serial channel single-fiber optical terminal packs and labels the received data of multiple serial channels separately and then sends it to the opposite end multi-serial channel single-fiber optical terminal through the optical fiber data transceiver channel. After the optical terminal receives it, it will The data is sent to the send queue of the corresponding serial channel and sent out. This completes data transmission in one direction. Multi-serial channel optical transceivers support full duplex, and data between a pair of optical transceivers can be transmitted simultaneously in both directions.