PROFINET Connector Symbol
Definition: The PROFINET Connector symbol represents an Industrial Ethernet network interface port used in PROFINET (Process Field Network) automation systems, depicted in schematic diagrams as a rectangular block labelled 'PN' with transmit (TD+, TD-) and receive (RD+) signal lines, conforming to IEC 61158 and IEC 61784 standards for fieldbus and industrial Ethernet communication.
Also known as: PN connector, PROFINET port, Industrial Ethernet connector, PROFINET interface, PN interface port.
What the PROFINET Connector symbol means
The PROFINET Connector symbol in a control-system schematic denotes a physical and logical interface point where a PROFINET-compliant device connects to an Industrial Ethernet network. PROFINET is the leading industrial Ethernet standard in Europe and globally, used to connect PLCs (controllers), I/O modules, drives, sensors, and HMI panels in factory automation networks.
The symbol communicates that the device at this node participates in a real-time Ethernet-based control network, exchanging cyclic process data and acyclic parameter data with a PROFINET controller (e.g. a Siemens SIMATIC S7 PLC). The connector carries 100 Mbit/s (PROFINET RT) or 1 Gbit/s (PROFINET IRT) Ethernet signals using standard RJ45 or M12 D-coded connectors.
How to identify the PROFINET Connector symbol
The PROFINET Connector symbol appears as a small rectangle with rounded corners labelled 'PN' in the upper portion, with a horizontal dividing line separating the label area from the pin area. Three vertical lines extend downward from the lower edge, representing the TD+ (transmit positive), TD- (transmit negative), and RD+ (receive positive) signal pins. This block layout is consistent with IEC 81346-based function-block notation for communication interfaces in industrial electrical diagrams.
Function in a circuit
The PROFINET connector provides the physical and electrical interface for connecting a device to a PROFINET Industrial Ethernet network. The TD+ and TD- pins carry the differential transmit pair, and the RD+ pin (with its implied RD- pair) carries the receive pair, conforming to 100BASE-TX or 1000BASE-T Ethernet physical layer standards. The connector enables the connected device (I/O slave, drive, sensor) to exchange real-time control data with a PROFINET controller at cycle times as low as 31.25 µs (PROFINET IRT), while also supporting device configuration, diagnostics, and parameter access via PROFINET acyclic services.
Standards: IEC vs ANSI
| IEC 60617 | IEC 61158-6-10 defines the PROFINET protocol data units and services. IEC 61784-2 specifies PROFINET communication profiles CP 3/1 (RT) and CP 3/2 (IRT). The physical layer follows IEC 61918 (Industrial communication networks — Installation of fieldbus systems). |
|---|---|
| ANSI/IEEE 315 | PROFINET is primarily governed by IEC standards. In North America it is also supported under IEEE 802.3 (Ethernet physical and data-link layers) and ANSI/ISA-S5.1 for instrument and control system documentation conventions. No dedicated ANSI symbol for PROFINET exists; IEEE 315 block-symbol conventions are used. |
| Key difference | IEC standards fully define PROFINET; ANSI/IEEE standards define the underlying Ethernet physical layer (IEEE 802.3) and general block-symbol conventions (IEEE 315). The schematic symbol is derived from IEC 81346 function-block notation rather than a dedicated PROFINET-specific IEC 60617 entry. |
Terminals / pins
| Pin | Name |
|---|---|
| td_p | TD+ |
| td_n | TD- |
| rd_p | RD+ |
Typical values
Network speed: 100 Mbit/s (PROFINET RT/IRT) or 1 Gbit/s (PROFINET IRT G2). Connector types: RJ45 (Cat5e/Cat6 cable), M12 D-coded (IP67 rated for field use). Maximum cable length between switches: 100 m (copper), 2000 m (fibre). Cycle time: 1 ms typical (RT), down to 31.25 µs (IRT).
Where the PROFINET Connector symbol is used
- PLC-to-I/O module connections in distributed I/O architectures (e.g. Siemens ET200SP, ET200MP remote I/O stations)
- Variable-frequency drive (VFD) network integration for speed and torque control via PROFINET RT from a PLC
- Robot arm and CNC machine tool integration in automotive and precision manufacturing cells
- HMI panel communications to PLC for real-time process visualisation and control
- Safety-integrated systems using PROFIsafe profile over PROFINET for SIL 3 / PLe safety functions
- Process automation field devices (flowmeters, transmitters) with PROFINET PA proxy interfaces
Example
In a bottling-line control schematic, the PROFINET Connector symbol on an ET200SP remote I/O module shows TD+ connected to the switch uplink and RD+ connected to the downlink, linking the remote I/O to the S7-1500 PLC controller at 1 ms cycle time for bottle-filling sequence control.
Key facts
- The PROFINET Connector symbol is a rectangular block labelled 'PN' with three signal pins: TD+ (transmit+), TD- (transmit-), and RD+ (receive+), representing a 100 Mbit/s or 1 Gbit/s Industrial Ethernet interface per IEC 61158 / IEC 61784.
- PROFINET (Process Field Network) is an open Industrial Ethernet standard governed by PROFIBUS & PROFINET International (PI) and standardised in IEC 61158 and IEC 61784-2.
- PROFINET RT (Real-Time) achieves cycle times of approximately 1 ms; PROFINET IRT (Isochronous Real-Time) achieves cycle times down to 31.25 µs for motion control applications.
- Physical connectors used with PROFINET are RJ45 (standard Cat5e/Cat6) for control cabinet use and M12 D-coded (IP67) for field devices in harsh environments.
- PROFINET devices have defined roles: controllers (PLCs), devices (I/O modules, drives, sensors), and supervisors (engineering/configuration tools).
- PROFIsafe is a safety profile that runs over PROFINET, enabling safety-rated (SIL 3 / PLe) data exchange over the same Ethernet cable as standard control data.
- PROFINET station names and IP addresses are assigned during commissioning using DCP (Discovery and Configuration Protocol), eliminating the need for manual IP configuration on each field device.
Frequently asked questions
What does the PROFINET connector symbol mean in a schematic?
The PROFINET connector symbol indicates that the device at that point connects to a PROFINET Industrial Ethernet network. It shows the network interface through which the device exchanges real-time control data with a PROFINET controller (PLC) per IEC 61158 and IEC 61784 standards.
What does the PROFINET connector symbol look like?
The PROFINET connector symbol is a small rectangle labelled 'PN' with a horizontal dividing line and three downward-extending pin lines representing TD+ (transmit+), TD- (transmit-), and RD+ (receive+). It follows the IEC 81346 function-block style used for communication interfaces in industrial schematics.
What standard governs PROFINET?
PROFINET is standardised in IEC 61158-6-10 (protocol) and IEC 61784-2 (communication profiles CP 3/1 RT and CP 3/2 IRT). The physical Ethernet layer follows IEEE 802.3 (100BASE-TX or 1000BASE-T). The standard is maintained by PROFIBUS & PROFINET International (PI).
What is the difference between PROFINET RT and PROFINET IRT?
PROFINET RT (Real-Time) uses standard Ethernet scheduling to achieve cycle times of approximately 1 ms, suitable for most I/O and drive control. PROFINET IRT (Isochronous Real-Time) uses time-synchronised hardware switching to achieve cycle times down to 31.25 µs, required for high-precision motion and synchronised axis control.
What connector type is used for PROFINET in the field?
Control cabinet PROFINET connections use standard RJ45 connectors with Cat5e or Cat6 cable. Field devices in harsh environments use M12 D-coded circular connectors (IP67 rated) that resist dust, moisture, and vibration per IEC 61076-2-101.
What are the pin labels on a PROFINET connector symbol?
The PROFINET connector symbol in circuit diagrams shows three pins: TD+ (transmit data positive), TD- (transmit data negative), and RD+ (receive data positive). The implied RD- (receive negative) completes the differential receive pair physically but may be omitted in simplified block symbols.
How does PROFINET differ from PROFIBUS?
PROFIBUS is a fieldbus standard using RS-485 serial communication at speeds up to 12 Mbit/s with a token-passing protocol. PROFINET uses standard Industrial Ethernet (100 Mbit/s or 1 Gbit/s) with TCP/IP and real-time extensions, offering higher bandwidth, faster cycle times, and integration with IT networks, while being backward-compatible via PROFIBUS/PROFINET proxy devices.
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