Cable & Wire | High quality and excellent service at reasonable prices.
info@zion-communication.com
Author: Michael Publish Time: 28-07-2025 Origin: Site
■ Which Cable Do You Require for RS485 Communication?
RS485 is a frequently applied differential serial communication standard in industrial automation, building control, and instrumentation networks. The most crucial aspect of any RS485 communication is the choice of cable, which will guarantee signal fidelity, data transmission reliability, and long-term efficiency. Through this guide, we will review what is required for the cable to be fit for RS485, which are some of the key parameters like impedance, shielding, conductor material, and cable construction.
Such considerations include the need for cable specification in RS485 communication:
RS485 makes use of a differential transmission on twisted pair cables, which extends its usable length and range in electrically noisy environments. Although the condition and construction of the cable are the factors that determine:
Amplified signal loss
Independently radiated power that creates a wave
Electromagnetic interference (EMI)
Distance and baud rate between devices
In such an instance, choice of the right cable for the RS485 application and site is sensibly an important factor.
■ Key Factors to Consider When Choosing RS485 Cable
An RS485 standard cable will have a nominal characteristic impedance of 120 ohms, which is always the first parameter to be specified. Cables that are outside of the standard value too much can create signal reflections that cause data errors.
✅ Recommended: Deploy twisted pair cables of 120 Ω ±10% impedance in domains.
RS485 signals must be carried over a pair of wires that are twisted together to ensure that any noise signal on the wires affects both wires equally, allowing the differential receiver to cancel the noise. Twisting also decreases crosstalk between multiple signal sets.
When it comes to a 2 wire RS485 applications, only one twisted pair is needed.
Twisted pairs for 4 wire RS485 should be used, with two (one for TX and one for RX).
✅ Tip: Coiling has better noise cutting performance.
In an industrial setting, there can be electromagnetic interference (EMI) from motors, power cables, or lighting, causing distortion of the RS485 signals. The kind of cable you choose will depend on the amount of electrical noise that it will assume:
Unshielded Twisted Pair (UTP): Suitable for short distances in low-noise areas.
Foil Shielded (FTP): Offers basic protection. Includes a thin aluminum/polyester foil.
Foil + Braided Shield (SFTP): Ideal for high-noise environments. Provides superior EMI shielding.
✅ The Charge: Ground one or both ends of the shield. Whose choice depends on the strategy of grounding. It is highly effective.
Ensure you pick cable with 100% bare copper conductors for maximum conductivity and minimal signal loss. Be careful to evade using copper clad aluminum (CCA) cable as it has a very low resistance and may cause signal loss.
Stranded copper: Flexible, easier to handle, can be installed in tight spaces.
Solid copper: Leads to better signal performance over long distances.
✅ Gauge Recommendation: Select 22 AWG or 24 AWG for the most situations of RS485 circuits.
While RS485 is the longest cable run option with a corresponding high baud rate, it is important to strike a balance.
Baud Rate | Max Cable Length |
10 kbps | 1200 meters |
100 kbps | 400 meters |
1 Mbps | 12 meters |
✅ Tip: If your application needs extended range and fast data transfer, you may want to try RS485 repeaters or increasing baud rate.
■ Example of Recommended RS485 Cable Structure
Here is a typical construction for a high-performance RS485 cable:
Component | Description |
Conductor | 2 x 2 x 24AWG stranded bare copper |
Insulation | Foam Polyethylene (FPE) |
Shield | Aluminum foil + tinned copper braid |
Drain Wire | Tinned copper, 24 AWG |
Jacket | LSZH or PVC |
Impedance | 120 Ω ±10% |
■ Conclusion: Without a Kettle, What is the Best Cable for RS485?
The perfected RS485 cable should meet the following requirements:
120-ohm low
Impedance
Twisted pair structure
Shielding entitled for the EMI environment
Conductors of copper
Correct diameter adjusted for the distance needed the distance and for the installation ambience
Through proper selection of the cable through the heading of RS485 communication parameters: transmission quality and system stability can be regained.
Q1: Can I have the CAT5 or CAT6 for RS485?
A: Sure, there are numerous CAT5e/CAT6 cables containing 100-110 Ω impedance and twisted pairs. These wires are not damaged though these are not ideal for critical processes or long runs. For outdoors, the shielded types are recommended.
Q2: What happens if the impedance doesn't match 120 ohms?
A: It may only constitute of signal reflections, data errors, and thus communication failures for data transmissions of higher baud rates or over long distances.
Q3: Do I need shielded RS485 cable?
A: Shield protection is required in conditions with high level of electrical noise and in short runs with low level of electrical noise it is suggested to use unshielded twisted pair.
■ Enhancement of Your RS485 System with High-Quality Cable
Zion Communication presents a comprehensive RS485 communication cable range that includes several shielding types in addition to different jacket types (PVC, LSZH, PE) for internal, external, and industrial conditions. Check out our product catalog or send us a message for tailor-made OEM/ODM solutions.
Need Help Choosing?
Let our experts help you select the ideal cable for your environment.
Contact us for more information
michael@zion-communication.com
+86 13757188184
