Serial Cables

A serial cable is a computer cable used for data transfer between devices via serial communication protocols, where data is transmitted one bit at a time. Serial communications cables mostly use the RS-232 (Recommended Standard 232) interface specification and are terminated with D-subminiature connectors such as the 9-pin DB9 or 25-pin DB25.

RS Hong Kong offers a selection of high-quality serial cables from leading brands, including Phoenix Contact, Startech, Molex, TE Connectivity, and RS PRO.

Types of Serial Cables

Serial cables are available in several configurations, each suited to a specific communication standard, device type, or installation requirement. Selecting the correct type depends on the interface standard in use, the connector format required, and whether legacy compatibility or modern integration is the priority.

RS-232 Serial Cable

The RS-232 serial cable is the standard serial comms cable for short-distance, point-to-point data communication between DTE (Data Terminal Equipment) and DCE (Data Communication Equipment) devices. Constructed from shielded cable and terminated with D-subminiature connectors, the most common configuration is the 9-pin serial cable using a DB9 serial cable connector, though DB25 variants remain in use across legacy installations.

RS-232 cables are widely specified for PLC-to-HMI communication, POS terminals, and industrial equipment across Hong Kong's manufacturing and automation sectors. Maximum cable length under the RS-232 standard is typically 15 metres at standard data rates, though lower capacitance cable can extend this in practice.

Null Modem Cable

A null modem cable enables direct serial communication between two DTE devices — typically two computers or a computer and a serial peripheral — without requiring an intermediate modem. The cable achieves this by crossing the transmit and receive lines internally, allowing each device to interpret the other's output correctly.

Null modem cables are used for direct PC-to-PC file transfer, serial device emulation, and legacy system configuration tasks. The serial cable connector format is typically DB9 female-to-female, though DB25 variants are available for older equipment.

USB to Serial Adapter Cable

USB to serial adapter cables bridge modern USB-only computers with legacy RS-232 serial devices, extending the operational life of installed equipment without requiring hardware replacement. The adapter integrates a USB controller and an RS-232 transceiver within the cable assembly, presenting a virtual COM port to the host operating system.

Common applications include configuring legacy networking equipment, connecting older laboratory instruments, and maintaining serial-interface industrial devices from a laptop or workstation without a native serial port. DB9 is the standard serial cable connector format on the RS-232 end.

V.35 Serial Cable

V.35 serial cables support higher data rates than standard RS-232, making them the preferred serial comms cable for WAN router and network switch connections where bandwidth demands exceed RS-232 limits. The V.35 interface uses a distinctive 34-pin block connector and is specified for synchronous serial communication in telecommunications and wide-area networking equipment.

V.35 crossover and straight-through configurations are both available, enabling connection between DTE and DCE devices or back-to-back device testing. The format remains relevant in Hong Kong's telecommunications infrastructure and legacy WAN installations.

Serial Printer Cable

Serial printer cables connect computers and peripheral devices equipped with RS-232 serial ports, predating the widespread adoption of USB and parallel printer interfaces. The cable transmits print data serially between the host and the printer, with DB9 and DB25 serial cable connector formats covering the majority of legacy configurations.

Point-of-sale receipt printers and industrial label printers with serial interfaces remain in active use across Hong Kong's retail and logistics environments, making serial printer cables a continuing requirement for maintenance, replacement, and system integration work.

Industrial Applications of Serial Cables

Serial cables remain an active part of Hong Kong's industrial and commercial infrastructure, providing reliable point-to-point data communication across sectors where RS-232 and related standards are deeply embedded in installed equipment.

Industrial Automation

Serial cables connect PLCs, HMIs, SCADA systems, and I/O modules across Hong Kong's manufacturing and process automation facilities. Where Ethernet has not yet replaced legacy serial interfaces, RS-232 cables and USB-to-serial adapters maintain communication between control systems and field devices without requiring full hardware replacement.

Point of Sale & Retail

Barcode scanners, receipt printers, cash drawers, and POS terminals across Hong Kong's retail and hospitality sectors rely on serial cable assemblies for reliable peripheral connectivity. Serial interfaces remain common in high-transaction environments where proven, low-latency communication is preferred over wireless alternatives.

Scientific & Test Instrumentation

Oscilloscopes, signal analysers, data loggers, and programmable bench instruments use serial cables for configuration, control, and data capture. Researchers and engineers in Hong Kong's testing and calibration facilities depend on RS-232 connectivity to interface instruments with logging software and automated test platforms.

Building & Access Control Systems

Security panels, intercom units, access controllers, and building management systems across Hong Kong's commercial and residential developments use serial cables for short-distance device communication.

Your Trusted Supplier for Serial Cables in Hong Kong

RS Hong Kong is a trusted serial cable supplier stocking a wide range of RS-232, null modem, USB-to-serial, and V.35 cable assemblies for industrial, commercial, and infrastructure applications. The range includes serial cables from RS PRO, Phoenix Contact, and L-Com, covering standard and specialist configurations across DB9, DB25, and V.35 connector formats.

Beyond serial cables, RS stocks a comprehensive range of computer cables, including FireWire cables, SATA cables, and SCSI cables, catering to data and connectivity requirements across IT, industrial, and engineering projects.

Browse the full range online and order for delivery across Hong Kong. For details on delivery timeframes and charges, visit our Delivery page.