Technology Zone
Industrial communication links flow meters, transmitters, valves and pumps to control systems and the cloud. This zone covers HART, PROFIBUS, PROFINET, Ethernet-APL, IO-Link, Modbus and OPC UA, plus the gateways, infrastructure and wireless systems that connect them.
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What this zone covers
Most process instruments still send their main value as a 4-20 mA signal. HART adds a digital layer on the same two wires, so the same loop also carries diagnostics, configuration and secondary values. That is why HART remains the most widely installed protocol in process plants.
A fieldbus replaces one cable per device with a single digital segment that carries power and data for several devices. PROFIBUS PA is the main process fieldbus; PROFIBUS DP and Modbus RTU connect drives, pumps and remote I/O.
Ethernet-APL brings Ethernet over two wires to the instrument, with power, 10 Mbit/s and intrinsic safety for hazardous areas. On top of it run protocols such as PROFINET, EtherNet/IP, HART-IP and OPC UA, so field devices become part of the plant network.
IO-Link connects compact sensors and actuators point-to-point to a master with standard cable. It is common in food, beverage and machine building, where it transmits values, parameters and diagnostics without analogue input cards.
WirelessHART, Bluetooth, LoRaWAN and cellular IoT remove cabling where it is costly or impossible: remote tanks, rotating equipment, temporary measurements and commissioning with a phone or tablet.
OPC UA and MQTT carry equipment data to SCADA, MES and cloud platforms. Information models such as PA-DIM and the OPC UA companion specifications give that data a common structure, which makes multi-vendor analytics and AI applications possible.
| Parameter | Typical range | Rule of thumb |
|---|---|---|
| Protocol supported by the control system | HART, PROFIBUS PA, PROFINET, EtherNet/IP, Modbus | Choose the protocol the DCS or PLC already speaks; a gateway adds cost and a point of failure. |
| Physical layer | 4-20 mA, RS-485, two-wire Ethernet-APL, standard Ethernet, wireless | The cable and the hazardous-area concept decide more than the protocol name. |
| Data rate | HART 1.2 kbit/s, PROFIBUS PA 31.25 kbit/s, Ethernet-APL 10 Mbit/s | Fine for a process value; too slow for bulk diagnostics or firmware updates over HART. |
| Power over the signal line | 4-20 mA loop, fieldbus segment, APL power classes | Check the power budget per segment before adding devices. |
| Hazardous-area approval | Ex ia/ib, FISCO, 2-WISE for Ethernet-APL | Device, switch and barrier must share the same explosion-protection concept. |
| Devices per segment | PROFIBUS PA typically 8 to 16, Ethernet-APL one device per switch port | Plan for spare capacity and for what happens when a segment fails. |
| Wireless update rate and battery life | WirelessHART 1 s to 60 min; battery 5 to 10 years at slow rates | Faster updates drain the battery; keep wireless for monitoring rather than fast control. |
| Device description files | EDD, FDI package, DTM, GSD/GSDML, IODD | Check that the file for the exact device revision is available for your host system. |
| Symptom | Likely causes | What to do |
|---|---|---|
| Handheld or host cannot find the HART device | No loop resistance (minimum around 250 ohm), wrong polling address, device in multidrop mode. | Check the resistor in the loop, scan all addresses and confirm the loop current is live. |
| Fieldbus segment drops devices at random | Poor or missing termination, too much cable length, shield grounded at both ends, power supply at its limit. | Verify one terminator at each end, measure segment voltage and signal level, and check the shield concept. |
| Diagnostics never reach the asset management system | HART not passed through the I/O card or multiplexer, wrong or missing device description. | Use HART-capable I/O or a HART multiplexer and load the matching EDD, FDI package or DTM. |
| IO-Link sensor not recognised by the master | Port configured as standard digital input, IODD version mismatch. | Set the port to IO-Link mode and load the IODD for the exact sensor article number. |
| Wireless device with poor reliability | Too few neighbours in the mesh, metal structures blocking the signal, gateway too far away. | Ensure at least three devices in range of each node, raise the antenna or add a repeater. |
Go deeper: industrial communication news and case studies · frequently asked questions
Equipment Guide
Anderson-Negele
Anderson-Negele is a global company specializing in the development and production of sensors and measuring equipment for hygienic applications. As your reliable and flexible partner, we aim to always provide you with the best solution for your process.
Vögtlin Instruments GmbH
Vögtlin is a Swiss developer of precision digital mass flow meters & controllers for gases serving a wide range of applications: Life Science, Biotech, OEM and many more. Our proven concept is more stable and reliable than other gas flow measurement technologies. More than 250.000 installed units to the most prestigious companies can confirm this.
VEGA Grieshaber KG
The VEGA Grieshaber KG product portfolio extends from sensors for measurement of level, point level and pressure to equipment and software for integration into process control systems.
VPInstruments
VPInstruments helps industrial companies gain easy insight into energy flows. Its solutions for compressed air, gas, and electrical energy monitoring enable users to identify losses, reduce costs, and optimize production utilities. With VPVision monitoring software, users can see exactly where, when, and how much energy can be saved.
UWT GmbH
UWT GmbH is one of the world’s leading manufacturers of level measurement technology offering innovative sensors for continuous and point level measurement in any kind of bulk materials, solids as well as in liquids, pastes and foam. Reliability, quality and flexibility – these are the core values which underpin the UWT philosophy.
Siemens Industry, Inc.
Siemens Process Instrumentation offers innovative measurement solutions to increase plant efficiency and enhance product quality. Siemens extensive portfolio of process instruments for flow, level, pressure and temperature measurement, provides critical data that enables you to optimize your process, reduce energy consumption and ensure safety.
Cole-Parmer
Cole-Parmer, an Antylia Scientific company is a global manufacturer of lab equipment and supplies for research and process.
Bronkhorst High-Tech B.V.
Bronkhorst High-Tech offers an extensive product range of thermal, Coriolis and ultrasonic flow meters and controllers. We offer numerous styles of both standard and bespoke instruments for applications in laboratory, machinery and industry and we closely cooperate with OEM’s in the field of customer specific designs for gas, liquid or vapour control.
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What this zone covers
Yes. It works with almost every control system and adds diagnostics and remote configuration at little extra cost. Many Ethernet-APL instruments also support HART-IP, so existing tools and skills carry over.
Ethernet-APL is the physical layer: two-wire Ethernet with power for the field. PROFINET is one of the protocols that can run on it, next to EtherNet/IP, HART-IP and OPC UA.
For compact sensors and actuators on skids, utilities and hygienic lines, where a short cable to a master is practical and hazardous-area requirements are limited.
Yes, if the devices are certified or registered by the protocol organisation and the host has the matching device description files.
WirelessHART is proven for monitoring and slow, non-critical control. Fast or safety-related loops normally stay wired.
Through an edge gateway that reads HART, fieldbus or Modbus data and publishes it with OPC UA or MQTT, or through Ethernet-APL devices that expose OPC UA directly.
Usually yes. A protocol converter maps the Modbus registers to the other network; check the update rate and the number of registers it can handle.
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