What Is a Profibus Cable? Types and Selection Criteria

A Profibus cable is a single twisted-pair, shielded communication cable that connects stations on the Profibus fieldbus; DP types have a purple sheath.

A Profibus cable is a single twisted-pair, shielded communication cable that connects stations such as PLCs, remote I/O stations, drives and operator panels on the Profibus fieldbus. Types used on the DP line are recognized by their purple sheath. Profibus is defined in the IEC 61158 and IEC 61784 standard series.

Types

• Profibus DP cable: For the DP line in factory automation. This RS-485-based line uses cable with a characteristic impedance of 150 Ω (cable type A); the DP cables in the catalog have a 1x2x0.64 mm (22 AWG) construction.
• Profibus PA cable: For the PA line that connects process instruments. The PA line runs at 31.25 kbit/s, powers the devices over the same two wires it communicates on and needs 100 Ω cable. A segment coupler is used between DP and PA.
• FC (fast connect) type: Built to be stripped in one step with a special tool and pressed into an insulation-displacement connector.
• Halogen-free (LSZH) sheathed type: A sheath that gives off little smoke in a fire; for tunnels and crowded buildings. PVC-sheathed types are for general indoor installation.

Selection criteria

1. Line type: Determine whether the line is DP or PA; the two cables cannot replace each other.
2. Speed and segment length: On DP the permitted segment length gets shorter as speed increases; repeaters are used on longer lines. For cable type A:

1. Installation and bending: In the catalog product data, the minimum bending radius is 7.5 to 15 times the cable diameter. For moving machine parts or cable chains, choose a cable whose datasheet states it is suitable for moving use.
2. Connector compatibility: DP connectors are designed for a specific cable outer diameter and construction; use FC-type cable with FC connectors.

Common mistakes

• Wrong termination: Termination must be switched on only in the connectors at the first and last station of the segment. Because the end termination is powered by the station, switching that station off can disrupt the line.
• Swapping the A and B cores: In the catalog cables the A core is green and the B core is red; the same color must go to the same terminal in every connector.
• Leaving the shield unconnected: The foil and braid shield must sit on the connector's shield clamp over a wide area.
• Using spur lines at high speed: Spur lines are not used at 3–12 Mbit/s; stations are connected one after another along the line.
• Confusing it with Profinet cable: Profinet is an industrial Ethernet cable with a green sheath (Profinet Cables).

Profibus cables in the catalog

The Profibus Cables category lists 7 active products from 5 brands (October 2026); all are sold by the meter.

Check the impedance and cross-section of the PA cable in its datasheet before use. Master modules that connect a PLC to the DP network and Profibus cards for drives are in the Communication Modules category.

Frequently asked questions

Can an ordinary shielded signal cable be used on a Profibus line?

No. A DP line needs 150 Ω impedance and low capacitance; general signal cables do not guarantee these values, and communication errors occur.

Are Profibus DP and Profibus PA cables the same?

No. DP cable has 150 Ω impedance for the fast RS-485-based line; PA cable has 100 Ω for the 31.25 kbit/s line that also powers the devices.

How many stations can be connected to one Profibus segment?

A segment holds at most 32 stations, repeaters included. With repeaters the whole network can reach up to 126 addresses.