Fieldbus: a vital element in IIoT

The original drivers for field level communications were to simplify field instrument configuration, reduce cabling and maintenance and enable the use of a variety of devices from different vendors. These objectives quickly grew when it was realised that the use of a fieldbus network could also bring huge ancillary benefits such as asset management, better process control, and the creation of more intelligent field devices.

In addition to the original process sensor values, fieldbus provided data on device status, diagnostic alerts, process variables, configuration parameters and much more. This additional information is continuously monitored to alert plant operations as to whether a device is correctly configured and operating optimally.

An obvious early benefit was the inclusion of this data in the enterprise’s asset management system, which could manage the static configuration data and apply data analytics to help detect failure conditions in the devices and plant before they caused a major process problem, safety issue or costly shutdown, effectively enabling predictive maintenance capability.

Reduction of engineering costs was another benefit. Field devices could be reconfigured from a safe area, routine instrument checks could be replaced with automated monitoring, and centralised management of plant wide instrumentation could be implemented.

Improved process performance could be achieved by smarter HART and FOUNDATION Fieldbus devices, with operators having the ability to track equipment operation, and with alarms being automatically generated to warn of deteriorating equipment operation.

As we look to the future, automation and computational capabilities look set to become even more vital to manufacturing operations, going way beyond today’s computer-aided manufacturing (CAM), computer-integrated manufacturing (CIM) and manufacturing execution systems (MES). Production will be defined by concepts such as the Internet of Things (IoT) and Cyber physical systems (CPS), brought together by Industry 4.0.

The aim of Industry 4.0 is to deliver greater flexibility to production and manufacturing processes by integrating the processes, data and the organisational services within an enterprise. Within this model every product to be made will contain all the necessary information about its production and manufacturing requirements; production equipment will network autonomously to optimise production taking into account the entire value chain; production flow/sequence is dynamically optimised. The human input will be to provide essential decision-making, supervision and planning.

“Based on an intimate knowledge of the entire production/manufacturing value chain, it will be possible to dynamically select the optimal production flow/sequence. However, without real-time production asset information, Industry 4.0 will be neither realistic nor achievable,” said Louis Meyer, director of Process Industries of Mitsubishi Electric’s Factory Automation-European Business Group. “HART and FOUNDATION Fieldbus represent an essential platform for providing this vital data, and we believe that these communication protocols are indispensable supporting technologies for Industry 4.0.”

To be able to optimise their entire value chain, users need to ensure that they have integrated communication across the complete automation pyramid – from field level to control level up to MES/MOM and ERP level – in both directions. 

Today’s process instrumentation have increased functionality and the ability to provide ever increasing amounts of both device and process related diagnostic data. “Industrial communication protocols at field level, which allow this information to be made available to the plant, cannot be overestimated,” said Kurt Polzer, senior consultant solutions & training for Siemens Industry Sector.    

Today, the most widely used fieldbus protocol is the 4-20mA signal with HART protocol,

followed by Profibus PA and FOUNDATION Fieldbus. A recent ARC study (2013 –2018) found that the compound annual growth rate of the market for pressure transmitters shows 4.7% for HART, 2.8% for Profibus PA followed by 2.4% for FOUNDATION Fieldbus. “Siemens integrates HART and Profibus PA in its Sitrans library, which makes it easy for our customers to integrate the data and features of our instrumentation beyond standard integration into Simatic PCS7-based automation solutions. This allows real control-in-the field-applications, for example, through the use of the dosing feature of a magnetic flow meter,” explained Polzer. 

To increase the availability and performance of a plant it needs to be transparent. “The diagnostic data and status of every component in the plant must be made available where they are needed without barriers,” said Polzer. “However, according to estimated figures supplied by FieldComm Group, 85% of over 40 million installed HART devices are currently connected to a system that does not support integrated HART communications. This means that a huge amount of diagnostic data is being lost in the field so cannot add value to the enterprise. Many of our customers are now using WirelessHART adapters and HART multiplexers to begin to access this valuable data.”

Availability is vital in most applications where the FOUNDATION Fieldbus protocol is used. To meet this customer need, Siemens developed a DP/FF-Link, which links Profibus-DP to a FOUNDATION Fieldbus segment. “The customer benefit is that both, Profibus-DP and FOUNDATION Fieldbus can support redundancy to increase availability. In the FOUNDATION Fieldbus segment this is done by ring redundancy. So, in case of a cable break or short circuit all FOUNDATION Fieldbus devices connected via an Active Field Distributor (AFDiS) – which can be installed in hazardous areas – are still in the network, so there is no loss of data and no impact to the plant availability.

“Industrial communication based on international standards such as HART and FOUNDATION Fieldbus, play a major role in digital plants and Siemens will continue to develop products, components and systems in hardware and software to enable our customers to create innovative, future-oriented automation solutions,” concluded Polzer.

According to Gerrit Lohmann, manager product group remote systems at Pepperl+Fuchs, HART-IP will play an increasingly important role in future installations of process automation plants. He said: “Most installed field devices already used existing HART capabilities to transfer analogue data into digital systems to enable diagnostics and asset management. Submitting measurement data is a standard procedure in HART and can offer real benefits for process control.  Increasingly, transmitting HART data over Ethernet using HART-IP, connects the well proven HART protocol with the IoT, making data available to much more clients which are sharing the same Ethernet infrastructure.

 

“Taking this one step further, it is now also possible to connect via wireless communication. WirelessHART and HART-IP provide the perfect combination to serve all industry needs as we move towards a digital future. Pepperl + Fuchs’ WirelessHART gateway device, WirelessHART GW, already offers this combination – it only requires users to connect a WirelessHART adapter to a field device and connect the HART-IP interface of the WirelessHART GW. This provides access to all of the field device information via Ethernet, making the devices a valuable part of the IIoT,” concludes Lohmann.

John Yingst, product manager for Field Device Manager (FDM) at Honeywell Process Solutions argues that HART and FOUNDATION Fieldbus communications are even more relevant today than they have been in the past and that the development work being undertaken by FieldComm Group is vital. “I believe that, in the excitement surrounding the potential of the IIoT, many are forgetting the important role that field level communications have to play. HART and FOUNDATION Fieldbus have both been proven over many years of use in the industrial sector and they really are the mainstay of process control today. Further, HART is really the only protocol used in safety devices and it is used extensively at field level. WirelessHART is now also gaining popularity, having proven its robustness in non-critical applications.

“Field level data can provide huge amounts of information which, if mined and brought up to higher levels and put into perspective is indispensable for the success of the IIoT. However, this data does need context. HART and FOUNDATION Fieldbus do not have the ability to present alerts and alarms in context – every value will have the same priority in the eyes of the protocol – so solutions that are able to add contextural priority and criticality are important. If the data can be presented in the proper context to a variety of different users it can add real value and can help reduce unplanned shutdowns.” Honeywell created Uniformance Asset Sentinel to do just this. It is able to bring together the real-time monitoring capabilities of Honeywell’s Asset Manager with historical analytics of Matrikon’s Equipment Condition Monitoring – a combination that is said to result in a unified calculation and event detection platform that is applicable to a broad set of industries and applications.

Henk Van der Bent, marketing manager field networks for Yokogawa Europe, added a word of caution to temper the excitement surrounding the IIoT. “In our experience many end-users are not fully exploiting the advantages offered by their fieldbus-enabled devices. Proper use of asset management solutions are vital to leverage the huge quantity of data from fieldbus-enabled devices.”

Asset management systems provide the platform from which to manage field devices. Fieldbus provides a wealth of information from the field, but this information flow needs to be well managed to prevent users being flooded with excessive alerts and alarms.  NAMUR NE 107 provides guidance in this respect.

However, automating the diagnostic capabilities within a plant fundamentally changes the role of the instrument technician, maintenance engineer, plant engineer and operator. Rather than routinely checking on device health and performing calibrations, the instrument technicians will need to collaborate with the system engineer, plant engineer and operator, monitoring the process from a central control room to make intelligent decisions based on the process and the diagnostic information available.

“Users are telling us that they have less experienced engineers in the plant today, which means that many are having to return to a more elementary methodologies and so are not able to reap the benefits of the diagnostic capabilities that are possible. If users want to make use of this information they first need to change their working philosophy and I believe that the lack of adequately training engineering staff will slow down the uptake of IIoT and the interest in moving towards Industry 4.0.”

According to Van der Bent, there needs to be a fundamental engineering mentality change and this can really only be initiated by the end-user and it needs to be an ongoing process.

According to Mark Nixon, director of research, process systems and solutions at Emerson Process Management, the IoT has been fundamental in connecting devices, equipment, and users together into an always-connected framework with applications such as machine health, predictive analytics, performance monitoring, and asset monitoring readily layering on top of this infrastructure creating an industrial Internet. “The industrial Internet presents machines as services, accessible to any authorised application that is on the network,” he said. “The scope of knowledge needed to contribute to a physical-world solution becomes smaller in the process. Making a furnace more efficient, for instance, might involve some combination of refining its mechanical and thermal elements (machine design) and making it run in better relation to the application it is supporting. The industrial internet makes it possible to approach these challenges separately: connect the furnace to a network and give it an API that guards against damaging commands, and the control problem becomes accessible to someone who knows something about software-driven optimisation.”

FieldComm Group has recognised the trends discussed by its vendors in this article and has taken up the challenge. Today, HART-based sensor network installations support diverse sets of applications including monitoring and control, equipment health, environmental health & safety, safety, and asset management and the standard continues to evolve to meet the latest requirements while at the same time ensuring existing installations continue to interoperate with the latest technology additions. Similarly, Foundation Fieldbus continues to evolve to support bus-based installations. 

Both HART and FOUNDATION Fieldbus now support NAMUR NE107 diagnostics which prioritise alerts and alarms and makes it possible to classify certain types of alerts/alarms and most vendors now include NE 107 functionality in their devices too.

Another FieldComm technology, FDI, will also very soon be available, unifying device descriptions across both buses and others and this this will be a key development in supporting both IoT and cloud-based architectures by providing standard meta-data. So, FieldComm Group technologies are continuing to innovate to make life easier for end-users.