Introduction: What Is a DB9 Connector with Cable?
A DB9 connector with cable, also known as a DB9 cable assembly, is a widely used serial interface solution for data communication and control systems.
Despite the growth of USB and Ethernet, DB9 connectors remain essential in industrial automation, instrumentation, embedded systems, and legacy communication networks.
Different communication protocols require different DB9 wiring definitions, making it critical to choose the correct cable type for reliable data transmission.
Types of DB9 Cable Assemblies
DB9 cable assemblies can be classified based on connector structure, wiring type, and communication protocol.
1. By Connector Gender & Structure
- DB9 Male to DB9 Female Cable
- DB9 Male to DB9 Male Cable
- DB9 Female to DB9 Female Cable
- Straight connector or right-angle connector
- Metal shell or plastic shell
- Screw-lock or thumbscrew design
These variations ensure compatibility with different devices and installation environments.
2. By Wiring Type
Straight-Through DB9 Cable
- Pin-to-pin connection (1→1, 2→2, etc.)
- Commonly used for RS232 DTE-to-DCE connections
Null Modem DB9 Cable
- Crossed TX/RX signals
- Used for DTE-to-DTE communication
DB9 Wiring Definitions by Communication Protocol
1. RS232 DB9 Cable
Keywords: RS232 DB9 cable, DB9 RS232 pinout
RS232 is the most common serial communication standard using DB9 connectors.
Typical Pin Definition (DTE):
- Pin 2 – RXD (Receive Data)
- Pin 3 – TXD (Transmit Data)
- Pin 5 – GND (Signal Ground)
Applications:
- PLCs
- Industrial PCs
- Modems
- Programming and configuration ports
2. RS485 DB9 Cable
Keywords: RS485 DB9 cable, DB9 RS485 wiring
RS485 supports long-distance and multi-drop communication, often using twisted-pair wiring.
Typical Pin Definition:
- Pin 3 – Data+ (A)
- Pin 8 – Data− (B)
- Pin 5 – GND
Applications:
- Industrial networks
- Building automation
- Energy monitoring systems
3. RS422 DB9 Cable
Keywords: RS422 DB9 cable, DB9 RS422 pinout
RS422 is a full-duplex differential communication standard.
Typical Pin Definition:
- Pin 2 – RX−
- Pin 3 – TX−
- Pin 4 – TX+
- Pin 5 – GND
- Pin 7 – RX+
Applications:
- Motion control systems
- CNC machines
- Long-distance point-to-point communication
4. CAN Bus DB9 Cable
Keywords: CAN DB9 cable, DB9 CAN bus pinout
DB9 connectors are widely used for CAN communication, following standardized pin definitions.
Common CAN Pin Definition (CiA 303-1):
- Pin 2 – CAN Low
- Pin 7 – CAN High
- Pin 3 – CAN GND
Applications:
- Industrial automation
- Vehicle networks
- Robotics and embedded systems
Cable Construction Options
- Shielded cable for EMI protection
- Twisted-pair cable for differential signals
- Industrial-grade PVC or PUR jacket
- Custom length and labeling
These options improve signal integrity and durability.
How to Choose the Right DB9 Cable Assembly
When selecting a DB9 connector with cable, consider:
- Communication protocol (RS232 / RS485 / RS422 / CAN)
- Pin definition and wiring type
- Connector gender and shell type
- Cable shielding and length
- Installation environment
Correct selection ensures compatibility and reliable performance.
Applications of DB9 Cable Assemblies
- Industrial automation systems
- Embedded controllers
- Measurement and testing equipment
- Transportation and energy systems
- Legacy communication interfaces
Conclusion
DB9 cable assemblies remain a reliable and flexible solution for serial communication.
Understanding the different DB9 connector types and protocol-specific wiring definitions—including RS232, RS485, RS422, and CAN—is essential for system compatibility and stable data transmission.
If you need custom DB9 cable assemblies, including specific pinouts, shielding, or industrial-grade cables, we offer engineering support, fast sampling, and OEM production.
Contact us today to find the right DB9 cable solution for your application.
