Serial Cables

What are these and what are their use(s)?

A serial cable is a cable used to transfer information between two devices using a serial communication protocol. The form of connectors depends on the particular serial port used. A cable wired for connecting two DTEs directly is known as a null modem cable.

Serial cables are used for the serial transmission of data. They support communication standards such as RS232, RS422, and RS485, as well as Fibre Channel, IEEE 1394 or FireWire® (Apple Computer, Inc.), and universal serial bus (USB).

Types of Serial Cables

  • RS232 cables support a typical transmission speed of 9600 bps at 15 m. They provide asynchronous communication capabilities with hardware flow control, software flow control, and parity checking. Most gears, instruments with digital control interfaces, and communication devices have an RS232 interface.
  • RS422 cables support multipoint connections and provide much longer transmission distances than RS232. The RS422 standard uses a differential transmission technology, and provides high-speed transmissions up to 10 Mbps over a maximum transmission distance of 1.2 km at 110 kbps.
  • RS485 cables are used in applications where a single controller needs to control multiple devices (up to 64). RS485 uses three-way instead of two-way transmissions, but is compatible with the RS422 interface. It provides a two-wire bus topology and provides a very inexpensive network system.
  • Fibre Channel cables consist of twisted-pair, coaxial, or fiber optic cables that use a high-speed, serial data transfer architecture. Small computer system interface (SCSI) devices can use Fibre Channel arbitrated loop (FC-AL), the most popular Fibre Channel typology. Using optical fiber, FC-AL supports full-duplex data transfer rates of 100 Mbps.
  • FireWire cables or IEEE 1394 cables are used for very fast digital data transfers such as streaming video. Applications include high-speed peripheral connections to personal computers, including hard disks, CD-ROMs, DVDs, graphics cards, high-speed scanners, and direct video.
  • USB cables use the universal serial bus (USB) standard for connecting computer peripherals such as keyboards, printers, and disk drives to personal computers (PCs). There are different numbered versions of USB, as well as micro and mini categories for each version.

Figure II-5: A diagrammatical representation of the most common serial data connectors. Cables we typically stock at Tekmart Africa.


Serial Cables