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Why Are Industrial Gateways Important to Smart Manufacturing Systems?
Jan
Summary: Industrial gateways, a broad term that also includes protocol gateways (aka protocol converters), are critical for manufacturing because they enable real-time data flow between legacy equipment and modern systems without replacing hardware or rewriting PLC logic.
What is a Protocol Gateway?
A protocol gateway is a type of industrial gateway that is dedicated to connecting machines, PLCs and industrial networks using different communication protocols and data formats. It translates and moves data reliably between systems that were never designed to talk to each other.
What is the Difference Between an Industrial Gateway and a Protocol Gateway?
The terms are related, with some overlap. A protocol gateway is a more specific version of the generic term industrial gateway. The broader industrial gateway term includes protocol conversion (acting as a converter/translator) but also provides aggregation, filtering, edge computing and security. This, more functional industrial gateway, is called an edge gateway.
The table below shows a comparison of key capabilities between protocol gateways and edge gateways in smart manufacturing environments.
| Industrial Gateways | ||
|---|---|---|
| Feature | Protocol Gateway | Edge Gateway |
| Protocol Conversion | ✔ | ✔ |
| In Zone Operation | ✔ | ✔ |
| Cross Zone Operation | ✔ | |
| Typical IEC 62443 Security Level | SL 1 | SL 2 or 6 |
| Publishing | MQTT, OPC UA, Direct to Database | |
| Aggregating, Filtering, Edge Computing | ✔ | |
What is a Production Zone?
The IEC 62443 standard defines a production zone as a single, well-defined, standalone process in a manufacturing system. In Zone and Cross Zone operation is one of the distinguishing characteristics of Edge protocol gateways. In Zone means communication entirely within a single zone. Cross Zone means communication from one production zone to another.
Why are Industrial Gateways Important to Smart Manufacturing Systems?
Smart manufacturing uses technology to create connected, intelligent factories that self-monitor and optimize production in real-time, boosting efficiency, quality and flexibility. Creating these data-driven operations means including devices, networks and systems that cannot directly communicate with the control system. Collecting data from these systems and making it available to Smart Manufacturing applications is the job of edge protocol gateways.
The image below shows an edge gateway securely connecting devices and networks within a production zone to devices and applications outside the production zone.
Connecting machine systems, networks and devices that have protocols that don’t natively connect to PLCs is the job of protocol gateways.
The image below shows a protocol gateway connecting devices and networks within a production zone. Never use a protocol gateway to connect devices outside a zone as protocol gateways are not typically cyber-secure.
Protocol Gateway Applications
Protocol gateway applications include:
- Integrating ASCII barcodes into PLC logic to optimize product flow through a production system
- Integrating package weights from a Modbus scale into PLC logic to perform quality checking of under-weight or over-weight packages
- Integrating temperatures of chilled water BACnet-enabled chillers to monitor the incoming process water supply
How Do Protocol Gateways Help Modernize Brownfield and Legacy Equipment?
Protocol gateways modernize brownfield and legacy equipment by allowing existing machines to share data without being replaced or reprogrammed. Devices that use serial, proprietary, or obsolete communication protocols can be connected and published to PLCs, historians, MES and analytics platforms.
What Key Features Should You Look for in Selecting a Protocol Converter?
Integrating equipment from diverse suppliers with non-standard communication protocols is a risky component of any plant floor project. Learning about the two protocols, managing diverse data types and formats and configuring operation of the protocol gateway is sometimes a costly, multi-hour project.
That risk can be alleviated by selecting an intelligent, standalone gateway that:
- Requires No Logic Slots
In-rack modules are expensive “slot-hogs” that consume valuable rack real estate and increase deployment time. - Requires No Logic Changes
Any new logic, specifically tied to a protocol gateway is not only expensive to generate but reduces long-term availability. - Is Simple to Configure
All suppliers claim, “simple configuration.” It’s wise to get colleagues’ recommendations and, failing that, to walk through the configuration setup with the supplier. - Provides Diagnostics
It’s critical that message counts, status data and the “raw” data streams from the devices are available. Troubleshooting the connection without this critical information is difficult. - Is Well-Supported
A control engineer is often very knowledgeable about one protocol, such as EtherNet/IP, but clueless about another, such as BACnet or SNMP. The ability to discuss an application with a knowledgeable support person without waiting for call backs, dealing with internet queues and scheduling applications is extremely important.
What Are the Limitations of Protocol Gateways?
- Response time – protocol gateways typically are not designed for applications with critical timing requirements. The latency of individual networks and a typical protocol gateway itself is such that sub-10 ms operation is often not realistic.
- Architectural misuse – a protocol gateway should only be used to move data inside a production zone. Industrial edge gateways should be used to move data between zones.
- Additional points of failure – gateways are an additional hardware component with at least one physical connection to each mating protocol. These are all additional points of failure.
- Cybersecurity risk – protocol gateways are not designed with the security features necessary for communication outside the production zone and are a cybersecurity risk in intra-zone communications.
Frequently Asked Questions:
Yes, protocol gateways can be added to control systems without any downtime. Some PLC gateways, for example, simply write to the A-B PLC data table and can be added at any time with no downtime.
EtherNet/IP is the most common for the Rockwell PLC architecture. PROFINET is the most common for the Siemens PLC architecture. Many other protocols are typically connected to A-B and Siemens PLCs by connecting them with a protocol gateway.
Protocol gateways are usually insecure by design, as they are designed to operate within a production zone. Edge gateways, on the other hand, are designed to move data across zones and require much more rigorous security measures.
Conclusion: Protocol gateways are critical to smart manufacturing because they enable legacy and incompatible devices to participate safely and efficiently in data-driven, real-time manufacturing architectures.
For more information visit the Real Time Automation Digital Library. RTA Enginerds are also available to assist with implementation questions and design assistance at solutions@rtautomation.com or 262-436-9299.
