Establishing Communication between S7-400 PLCs (5km)

Dear User,

Several options exist for communicating between two S7-400 PLCs located 5km apart. Here's a breakdown of possibilities, including wireless considerations:

Wired Communication Options:

• Fiber Optic Cable: The most reliable option for this distance. Immune to electrical interference and supports high bandwidth. Learn more about Fiber Optic Communication
• PROFIBUS (with Fiber Optic Transceiver): PROFIBUS can be extended using fiber optic transceivers for longer distances.
• Industrial Ethernet: Possible with suitable media converters (e.g., fiber optic) and potentially repeaters depending on bandwidth requirements. Industrial Ethernet FAQ
• Serial Communication (RS-485 with Converters): Least recommended for 5km due to signal degradation, but feasible with repeaters and converters.

Wireless Communication:

Wireless communication is possible, but requires careful consideration:

• Point-to-Point Wireless (e.g., using SCADA radio modems): Requires line of sight and careful frequency planning to avoid interference. Not a standard S7 communication protocol; requires custom programming.
• Cellular (3G/4G/5G): Requires cellular modems for each PLC and a data plan. Introduces latency and security concerns.
• Wireless LAN (WiFi): Limited range; likely requires repeaters and a secure network setup.

Important Considerations:

• Latency: Wireless options generally introduce higher latency than wired connections.
• Security: Wireless communication needs robust security measures.
• Reliability: Wired solutions are generally more reliable than wireless.
• Bandwidth: Choose a solution that meets your data exchange requirements.

For detailed configuration guidance and component selection, please consult the Siemens documentation and consider engaging a Siemens expert. You can find more information on SiePortal.

Best Regards,
Siemens Self Support