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Parallel and serial data transmission

Serial and parallel data transmission are two basic methods for transferring data between devices or within systems. They differ in the way in which the data bits are sent. Serial data transmission is usually 9-pin and transmits the bits one after the other. The 9-pin plugs and sockets replaced the original 25-pin standard in the 1990s. 9-pin, 25-pin and more can be found in the INTOS ELECTRONIC AG® online shop. As the data is transmitted one after the other, the serial interface only requires one line, whereas parallel data transmission requires several lines. For example, if eight bits are to be transmitted, eight lines are required.

Serial or parallel interface? Simultaneous transmission or one after the other? The decision in favour of or against parallel or serial data transmission depends on various factors. These factors include speed, distance and the size of the data.

Advantages of serial data transmission compared to the parallel interface

Serial data transmission is particularly suitable when sending and receiving has to take place over a greater distance or only a limited number of lines are available. As only one data line is used, the hardware is simpler and more cost-effective. However, there are limitations in terms of transmission speed. As all bits are transmitted one after the other in an ordered sequence, the speed per line is lower than with parallel data transmission. However, this disadvantage is no longer necessarily true due to the acceleration of new networks and technologies. Serial cables, on the other hand, are less susceptible to interference. In detail, this means that there is less crosstalk or signal interference between the lines. Serial data transmission is also characterised by simple implementation. Examples of serial interfaces are USB, I2C or RS-232.

Parallel data transmission for short distances

Parallel data transmission makes up for the supposedly low speed of the serial interface. It is particularly suitable when speed is more important than the simplicity of the cabling. The parallel interface transmits data best over a short distance and, above all, simultaneously. However, this interface requires eight lines for one byte. As a result, it achieves a higher data transfer rate than its serial counterpart. Parallel data transfer is therefore increasingly being used in computer systems instead of serial, for example to enable data transfer between the processor and memory. However, the parallel interface requires several lines, which is why the cabling can be more complex and also more expensive. Furthermore, exact synchronisation of the lines is necessary in order to avoid different runtimes and thus faults. Examples of the parallel interface are the parallel port, which was previously used for printers, DIE, the former standard for hard disk connections, and PCI, which is used to connect hardware components within a computer.

Whether serial or parallel interface, discover the variety of our range in the INTOS ELECTRONIC AG® online shop.