Communication Distances (Serial; Profibus; MPI; Ethernet)

In SIEMENS industrial communication, the most commonly used methods are Serial; Profibus; MPI; and Ethernet communication. The maximum communication distances for each are described in the table below.

Serial Communication

Type	Rate	Maximum Distance
RS 232C	300~115200bps	15 m
20 mA TTY	9600 bps	1000 m
19,200 bps	500 m
422/485	115.2 kbps	250 m
38.4 kbps	500 m
19.2 kbps	1200 m

Note: The maximum distance data in the table assumes that both communication interfaces are isolated. If either interface is non-isolated, the maximum communication distance is 50m. The distance can be extended by adding a third-party 485 repeater (Siemens does not provide repeater devices for serial communication).

Profibus Communication

Standard Profibus cable:

Transmission Distance	Maximum Length of Bus Segment Cable	Maximum Distance Between Two Stations
9.6 to 187.5 kbps	1000 m	10000 m
500 kbps	400 m	4000 m
1.5 Mbps	200 m	2000 m
3 to 12 Mbps	100 m	1000 m

Note: The maximum distance for the PROFIBUS bus can be cascaded through 9 repeaters, so the maximum distance between two stations is calculated based on 10 bus segments.

It is recommended to use Siemens-specific Profibus cables, as third-party cables cannot guarantee connection stability and communication distance.

For ordering numbers of Profibus cables, connectors, and repeaters, please refer to the document: Common Accessory Ordering Numbers

Profibus Fiber Optics:

Fiber Type	Maximum Distance Between Two Stations
Standard Plastic Fiber Optic Cable	The maximum distance when connecting to OLM/P can reach 80 m, while connecting to devices with integrated optical interfaces and OBT can reach 50 m.
PCF Fiber Optic Cable	Length can reach 400 m (OLM) or 300 m (devices with integrated optical interfaces, OBT)
Multi-mode Glass Fiber	3 km
Single-mode Glass Fiber	15 km

MPI Communication

Transmission Rate	S7-300 CPU (Non-isolated MPI Interface)	CPU 314C-2 PN/DP, CPU 315-PN/DP, CPU 317, CPU 319
19.2 kbit/s	50 m	1000 m
187.5 kbit/s
1.5 Mbit/s	—-	200 m
3.0~12 Mbit/s	—-	100 m

Ethernet Communication

Cable Type	Maximum Distance Between Two Stations
Siemens Standard Network Cable and Connectors	100m
Standard Plastic Fiber Optic Cable (POF)	50 m
PCF Fiber Optic Cable	100 m
Multi-mode Glass Fiber	2km
Single-mode Glass Fiber	26km

Note:

1. It is recommended to use Siemens standard network cable connectors; for ordering numbers, please refer to the document: Common Accessory Ordering Numbers

2. Third-party network cable connectors are allowed, but due to the shielding performance and quality of the cables, the maximum communication distance cannot be guaranteed.

3. Industrial-grade switches can be used to extend communication distances. Each additional switch device can extend the “Maximum Distance Between Two Stations” in the table; theoretically, the communication distance can be extended indefinitely.

4. The maximum communication distance between two stations in industrial Ethernet or PROFINET networks may vary depending on the devices used. For example, multi-mode glass fiber may achieve a communication distance of 3 km, while single-mode glass fiber may achieve a communication distance of 120 km.