PN/MQTT Coupler

The MQTT protocol has become established in recent years as a simple transmission protocol for messages in the IoT world. MQTT stands for “Message Queue Telemetry Transport Protocol” and is an OASIS standard. The MQTT protocol always uses a central broker for communication between devices, which receives messages from, for example, a sensor and forwards them to interested devices, such as a control unit. When a sensor sends data to the broker, it is called a “publish”. If a device needs data, it must subscribe to the broker (“Subscribe”). The broker delivers the data to all subscribers when new data has arrived from the publisher.

With the PN/MQTT Coupler it is possible to transfer values between a PROFINET machine (PLC) and a MQTT broker. It is possible to send values from the PLC via PROFINET to a broker (“Publish”) as well as to subscribe values from a MQTT broker and receive them in the PLC via PROFINET (“Subscribe”).

The integration into the PLC engineering tool is enabled by a GSDML file, an extra configuration software is not necessary. All settings for the MQTT connection can be done on the web page of the device. MQTT brokers can be connected locally in the own network (“On premise”) as well as via the internet in the cloud.

Direct integration into the PLC puts full control of the data exchange with the IoT world in the hands of the programmer.

  • Supports the OASIS MQTT standards V3.1.1 and V5
  • Easy assignment of IO data via GSDML file
  • Up to 100 values can be configured for transmission simultaneously
  • Flexible configuration via web browser
  • Separate networks for PROFINET and MQTT connection
  • Connection to brokers in the local network or directly with the "cloud
  • Authentication (password, certificate) and encryption (TLS)
  • Supports AWS IoT, Microsoft Azue, HiveMQ, Siemens Mindsphere (in preparation)
  • Very compact design for DIN rail mounting
  • Redundant power supply
  • Galvanic isolation of the networks
PROFINET interface (X1)
Number1 with 2 ports
ProtocolPROFINET IO as defined in IEC 61158-6-10
Physical layer100 Mbps full duplex
I/O image sizemax. 1024 bytes input and output data
Connection2x RJ45
integrated switchYes
FeaturesPROFINET Conformance Class B (in preparation), Media redundancy (MRP client), Automatic addressing, Topology detection (LLDP, DCP), Diagnostic alarms
MQTT interface (X2)
Number1 with 2 ports
Connection2x RJ45
ProtocolMQTT V3.1.1 & V5
Transmission rate10/100 Mbps, full/half duplex
Status indicator9 LEDs function status, 8 LEDs Ethernet status
Voltage supply
Voltage supply24 V DC (18 - 28 V DC)
Current drawmax. 210 mA
Power dissipationMax. 5 W
Ambient conditions
Ambient temperature0 °C to 60 °C
Transport and storage temperature-20 °C to 80 °C
Protection ratingIP 20
CertificationsCE, PROFINET Conformance Class B (in preparation)



PN/MQTT Coupler700-162-3MQ02


Easy connection of fieldbus networks – with Helmholz PROFINET gateways Versie: 10-2023


PN/MQTT Coupler, Quick Start Guide Versie: 6
PN/MQTT Coupler, manual Versie: 4

Technische documentatie

PN/MQTT Coupler, PROFINET-Certificate Versie:


PN/MQTT Coupler, GSDML Versie: V2.41 - 20220402


IPset Versie: 1.04.016
PN/MQTT Coupler, Firmware Versie: V1.10.002