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最後編輯於 2025-11-04
Cable Lengths for Various Industrial Applications – FAQ
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Cable Lengths for Various Industrial Applications – FAQ
Cable length is a frequently discussed topic in industrial environments. Different types of signals and communication protocols have specific requirements for cabling, and following these guidelines is essential for reliable device operation. Below is an overview of the most common signal types and communication interfaces, including recommended maximum cable lengths.
Analog Signals
Question: What is the maximum recommended cable length for analog sensors?
Answer:
- Voltage signals (0…10 V, -10…+10 V): Recommended maximum cable length is 15 meters. Longer cables may be used if properly shielded and routed away from interference sources, but signal accuracy may be affected.
- Current signals (4…20 mA, 0…20 mA): These signals are more resistant to noise and voltage drop. Recommended cable length is up to 150 meters.
Note: In both cases, high-quality shielded cables and proper termination are assumed.
IO-Link
Question: How long can the cable be for IO-Link sensors?
Answer:
- Maximum cable length is 20 meters.
- Uses an unshielded 3-wire (at least) cable with a minimum cross-section of 0.34 mm² (AWG22).
- Shielding is not required, but the cable should not be routed near strong sources of electromagnetic interference.
Network Communication Protocols
Question: What are the maximum cable lengths for common industrial communication protocols?
Answer:
- Ethernet (Cat5e/Cat6): Maximum cable length is 100 meters. Commonly used for standard LAN communication with RJ45 connectors and twisted pair cables.
- Profinet: Uses the same physical layer as Ethernet, i.e., Cat5e or higher cables. Maximum length is also 100 meters.
- EtherCAT: Also Ethernet-based, with a maximum cable length of 100 meters between devices. For longer distances, fiber optics or repeaters can be used.
Practical example:
Documentation states that for CMTK (BNI00L2), the maximum network cable length is 30 meters. For IO-Link master modules, the maximum cable length is 100 meters. Therefore, if you use one CMTK (BNI00L2) and connect several masters in series, the following applies: the first connection from the higher-level system to the CMTK can be up to 30 meters, while the connection between the CMTK and the first master, as well as between individual masters, can be up to 100 meters.
Recommendations
- Always use cables that meet the specifications of the respective protocol.
- Ensure proper termination, shielding, and routing away from interference sources.
- If the application is electrically noisy or requires longer cables, consider using digital interfaces or fiber optics.