Standard protocols VS proprietary in the automation world



Early automation systems were not interoperable as most manufacturers were developing their own protocols of communication. As a result, these protocols designed by different builders were incompatible.

With the advent of increasingly sophisticated and flexible systems, facilities operators frequently found these incompatibilities to be serious obstacles for improving the performance of their installations. It was difficult if not impossible to integrate automation and control systems into a single, integrated one.

Individual manufacturers have therefore attempted to build interoperability into their protocols to allow the integration of other systems. While this approach allows the association of previously separate and independent systems into a single one, it has its drawbacks. With proprietary protocols, installations managers are locked into one manufacturer's system.

On the contrary, standard protocols provide users with a wider choice of systems and devices but also offer easier communication with subsystems.

What is a standard exactly?

A standard is a set of recommendations developed and recommended by a representative group of users.

There are two different types:

  • De jure standard, having been developed within a framework that respects the rules of representativeness of the different actors or representation by nation, followed by adoption by a nationally or internationally recognized body. This type of standard is open in principle. For example, IEC 610870-5-104, IEC 61850 (IEC TC57), CIM (IEC TC57 and the CIM user group).
  • De facto standard, a custom or a convention established by groups of manufacturers and/or users. They are generally open in the sense that its specifications are available, at least for a certain category of players in these markets. For example, BACnet (ASHRAE), OPC (OPC foundation), DNP3 (DNP user group), OCPP. Some of them have also been adopted as standard by recognized bodies.

Standards make it possible to ensure the durability and scalability of product and technical choices and promote the interoperability of platforms. It is also a compendium of best practices.

In the case of heterogeneous systems, the existence of interoperable products based on standards for interfaces between subsystems is a prerequisite for developing such solutions.

Among the multitude of standards available on the automation market, we find IEC 60870-5-104, IEC 61850, OPC, BACnet, SNMP[1], SYSLOG, Modbus and MQTT[2] to name a few.

Here is a short overview of some of the main standard protocols in the fields of energy, industry and building:

- IEC 61850 developed and adopted by the IEC, its purpose lies in the implementation of digital communication systems in electrical substations.

The aim is to take advantage of modern communication networks offering high bandwidth, as well as digital equipment (IED – Intelligent Electronic Device) with processing capacities far superior to those of previous generations (IEC 104). These developments make it possible to consider the replacement of all or part of the wired logic in favor of programmed logic and data exchanges on digital buses at field and bay levels.

OPC was originally developed to link Windows applications and process control hardware and software. The protocol then expanded beyond process control to allow multi-platform implementations.

OPC UA, its latest unified architecture, is not only scalable and flexible in its implementation, it is above all independent of any manufacturer for industrial automation applications. It also natively integrates security and is recommended by several organizations for the safety and defense of information systems.

The OPC Foundation is responsible for creating and maintaining the necessary standards and cooperating with industry market leaders.

BACnet™ is an open and vendor agnostic communication standard designed and maintained by the ASHRAE[1].

Originally designed for the management of ventilation and air conditioning systems, it has been enriched to adapt to the needs of Building Management in general. It is now used very largely and can be applied to virtually any type of system present in buildings today. It can also use a wide range of network technologies for communications such as Ethernet TCP/IP, LonTalk, Arcnet, PTP, MS/TP.

As it can be implemented freely, its integration level depends on the implementation. The BACnet Testing Laboratory has therefore defined a list of software and hardware for their integration level validating the way they implement BACnet according to several profiles (B-AWS*, B-OWS, B-OD,…).

OCPP (Open Charge Point Protocol) is a communication protocol for exchanging data between charging stations and a charging station management system, also known as a charging station network, similar to cell phones and cell phone networks.

The OCPP standard is maintained and promoted by the Open Charge Alliance. They have currently accredited 5 tests labs for certified implementations.

ICCP (Inter Control Center Protocol) is a protocol that connects control center, providing data exchange between entities in the energy industry. This protocols uses MMS (Manufacturing Message Specification) to deliver the frames. MMS is an international standard (ISO 9506) dealing with messaging systems for transferring real time process data and supervisory control between networked devices or computer application services messaging.

- MQTT (Message Queuing and Telemetry Transport) is a publish/subscribe protocol designed for SCADA and remote networks. MQTT can be deployed using various type of networks (WiFi, Ethernet,4G,…). Like HTTP & LoRa, MQTT provides the transport but does not define the presentation of the data. It uses an application specific message structure** called “payload” such as JSON for example. This means that MQTT is not “plug & play” and may lead to interoperability issues depending on the payload.

- LoRa, Sigfox are low power wide area protocols (LPWAN) carrying very small messages in a long range distance using radio frequencies. They can be implemented both in private networks (privately managed) and in operated networks (managed by an operator). These protocols allow handling numerous self-powered and wireless devices.

SNMP is a protocol allowing network administrators to manage network equipment in real-time and diagnose network and hardware potential issues remotely. This standard allows access to a wide range of information used for monitoring and diagnostic of network infrastructure and devices such as switches, routers, firewalls, end-points. Polling but also event-based messages sent by the device on specific events are supported.

SYSLOG is a protocol dedicated to message logging. Computer system designers may use syslog for system management and security auditing as well as general informational, analysis, and debugging messages. A wide variety of devices, such as printers, routers, and message receivers across many platforms use the syslog standard. This permits the consolidation of logging data from different types of systems in a central repository which is often cyber security oriented like SIEM (security event information management). Implementations of syslog exist for many operating systems.


While standards are supported by the product and services of many different companies and organizations, it is important to note that standard implementation does not always equal operability.

To require a standard is to better define one's need but the standard can be badly implemented, hence the user must remain vigilant as for the perimeter of certification of the supplier. The latter should also stay involved for maintenance after implementation and also have a vision on the evolution of the standard.

At ARC, we endeavor to provide all PcVue Solutions users interoperability and open systems through certified implementations of open standards.

We have based our developments on adherence to the accepted industry standards that facilitate the interoperability of its products with third-party applications.

This is why we have been engaged for years in various standardization activities as an active member of working groups such as BACnet, IEC, OPC, DNP and KNX among others.


Want more details on a specific driver in your market? Don’t miss our upcoming PcVue Master Series (videos and articles) on standard protocols by sector!


[1] Simple Network Management Protocol

[2] Message Queueing and Telemetry Transport

*PcVue is listed with the highest profile (B-AWS) by the BACnet Testing laboratory

**PcVue IoT Hub provides a kind of payload reader natively integrated


Long-life installations
Getting IIoT data into a SCADA system

By accepting you will be accessing a service provided by a third-party external to