Living with Serial Production Equipment in an Industry 4.0 World

By Harry Forbes



Industry 4.0 initiatives and general plant modernization efforts typically require integrating older production equipment and machines that often have serial rather than Ethernet interfaces.  Factory appliances, such as modern industrial device servers and protocol converters, can serve this need effectively.

Living with Serial Production Equipment in an Industry 4.0 World

The Industry 4.0 vision is one of autonomous collaboration of production equipment and machines to make factories and plants more flexible, improve productivity, and reduce waste. But many machines and systems serial production equipment Living%20In%20a%20Serial%20World.JPGthat need to participate in I4.0 have been in place for 10, 15, or even 20 years.  Factory engineers wonder “How can I move forward toward Industry 4.0 when I have so many machines that still aren’t even on my network?”  It’s a good question. 

Long-lived equipment and legacy devices mean that factories and plants still have many machines with serial interfaces rather than Ethernet.  Currently, these serial interfaces are often only used for diagnostics, making them a potential source of information for I4.0 activities.  But first they must be integrated with more modern systems.  Factory appliances, such as device servers, can do this by integrating these legacy information “outliers” as plant systems are modernized and I4.0 activity proceeds.

By definition, a device server integrates serial interfaces (RS-232, RS-422, or RS-485) to a modern local area network (LAN).  In contrast, a protocol converter converts the protocol of one device to that of another to achieve interoperability.  A protocol converter can come in one of two types.  One connects two serial fieldbusses with each other while the other, possessing an Ethernet interface, connects serial and Ethernet industrial protocols like ModbusTCP, PROFINET, or EtherNet/IP.   These appliances are also commonly called “gateways” although in formal network terminology a gateway provides higher level functionality, such as internetwork routing.

Industrial Requirements

Industrial customers would be happy to deploy device servers and protocol converters, but not if the installation creates operational or maintenance headaches.  They need to choose appliances with these industrial features:

Industrial design - Equipment needs to be specifically designed for use industrial environments rather than for commercial or data center use.

serial production equipment Typical%20Modern%20Industrial%20Device%20Servers.JPGCompact, installable - Since these appliances are additional equipment installed within existing cabinets, compactness and ease of installation are crucial.  DIN-rail mounting and 24 VDC power are typically preferred.

Simplicity - While the products are industrial, simplicity and ease of use are also crucial.  Such appliances will be commissioned or diagnosed rarely.  Therefore, simple setup tools and well-chosen default parameters save time when commissioning and require little or no training time.

Security - Cybersecurity is a major consideration for any industrial installation today.  Small appliances are no exception. Some device servers have been shown to have major vulnerabilities and have had their firmware infected with malware to the extent that the devices had to be physically replaced to remove the malware.  

Reliability and diagnostics - Again, since they are not a major focus of OT, the appliances need to be highly reliable and should have effective and easily integrated diagnostics so that problems are rare and minimal troubleshooting is required.

Device Server Use Cases

There are a wide variety of use cases for applications for older equipment I4.0-enabled by device servers.  Here are just a few.

Machine access and energy - A food manufacturer wanted to reduce waste in some energy-intensive machines that ran continuously even when not producing.  Process engineers changed the machine’s control logic to enable automatic shutdown along with a start permissive set by a bar code reader. Employees could satisfy the start permissive by scanning the bar code on their personal ID badges.  This change prevented the machine from running continuously.  A device server integrated the bar code readers with the PLCs that controlled the machines.

serial production equipment Device%20Server%20Integrating%20Serial%20Bar%20Code%20Reader%20with%20EtherNet-IP.JPG

Material handling – Automotive assembly requires parts to arrive precisely on time when needed for a specific unit.  In one case, bar codes on car doors were read and a PLC in the automation system used that information to route the AGV that then carried the doors to the proper line for assembly.

Legacy equipment – Old control system PLCs had only an RS-232 interface, no longer available on modern laptop computers. The manufacturer installed device servers in the PLC cabinets to enable technicians to diagnose the PLCs either locally or remotely.

Example of Phoenix Contact Product Family

As ARC Advisory Group learned in a recent briefing, products such as the Phoenix Contact family of device servers and protocol converters can provide a solution for integrating legacy serial devices into modern industrial networks.  These compact, fan-less, DIN rail-mounting units with operating temperature ranges of -40° – 70°C and IP 20 ratings also carry many other EMC and agency approvals. A variety of models can serve the most common industrial serial protocols (see following table).  Features that match end user requirements include:

Ease of use – An embedded web server provides the interface for configuration, diagnostics, and troubleshooting.  The embedded web server includes a diagnostic terminal that enables technicians to view serial data streams and diagnose any issues with the serial interface.    For consistency, the web interfaces are common across all the device server products.

Security – Device servers feature AES encryption for transmitting sensitive data.  They can also be equipped with certificate-based authentication, preventing their use even by intruders who know the administrative account name and password.

serial production equipment Phoenix%20Contact%20Device%20Server-Protocol%20Converter%20Products.JPG


  • For modernization programs such as Industry 4.0, industrial device servers can integrate older production machines and equipment at very reasonable cost
  • Strong cybersecurity is a must for such devices since, in the past, some have been specifically targeted for malware attacks
  • When choosing this kind of equipment, look for industrial specifications and simplicity, since these devices play a supporting role


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Keywords: Device Server, Gateway, Industry 4.0, Phoenix Contact, Protocol Converter, ARC Advisory Group.

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