Continuous Improvements in PROFINET

Continuous Improvements in PROFINET

 
By Bill Lydon - Editor, January 2011
 
Carl Henning, Deputy Director of PI North America, and I recently discussed the automation industry, PI North America organization, and PROFINET technology developments.
 
Name Change
 
This summer PTO changed its name to PI North America to more closely identify with the international umbrella organization for the Regional PI Associations. PI North America is one of 27 Regional PI Associations around the world. PI North America joins PI Switzerland, PI Southeast Asia, and PI Italia in migrating to the new naming convention. PI North America was founded as PROFIBUS Trade Organization in 1994 as an autonomous non-profit trade organization and shortened the name to PTO about five years ago. PI North America has the same office, same phone number, and same URL: www.us.profibus.com.  
 
PROFIenergy
 
Henning noted that there continues to be more products added with the PROFIenergy profile.  
 
PROFIenergy is a profile of the PROFINET communications protocol that allows the power consumption of automation equipment to be managed over a PROFINET network. The elaborate engineering required for energy-saving functions must often be carried out specifically for each device, which, to date, has been a major obstacle for the implementation of energy-saving measures. The PROFIenergy profile simplifies this by creating a standardized interface for energy logic. PROFIenergy relies on three production elements working together - the controlling device in an automation network (usually a PLC, but it could be a supervisory system or dedicated energy management controller on the same network), the communications network (PROFINET), and the power consuming unit (which could be a single device, work cell or even a larger sub-system). The controlling device transmits signals via PROFINET to indicate when production pauses will happen. Each unit then determines how this information is to be handled. Application engineers decide how to implement the best energy management strategy by embedding a software ‘agent’ in the equipment firmware that responds to the PROFIenergy commands in ways that suit the application. For example, a production cell may need a conveyor to be slowed down before a robot can be put into ‘sleep’ mode. If the duration of a pause is long enough, perhaps the unit can be completely disconnected. PROFIenergy can also transmit power demand information back to the controller to support more sophisticated energy savings schemes, including peak load management, load rolling, or custom schemes. Other, non-electrical, energy-consuming equipment could also be managed. 
 
The basic energy states supported include: brief pauses, long pauses, and unscheduled pauses. Brief pauses (say up to one hour) are generally planned - e.g. lunchtime breaks – enabling devices to be routinely switched off. Safety-related functions are protected. On restart, the system restarts devices in a switch-on sequence and checks that they all have started up correctly. The production process is then restarted. Longer pauses (typically hours or days) are similar but additional devices can be put into standby or switched off completely, or deeper ‘sleep’ modes can be initiated. Unscheduled pauses (typically breakdowns) are also similar, but the user doesn’t know when they will happen or the duration. Initially, devices are put into a ‘stop’ condition to reduce energy consumption. Depending on duration, equipment can be switched into further energy-saving states if required.
 
The profile supports measuring and visualization of the electrical load when data is collected from the equipment either directly (by instrumentation) or implicitly (by knowing the electrical parameters). Knowing when, where and how much energy is required could lead to more effective energy strategies. The energy consumption of a machine can also be visualized and archived on an HMI. This provides operations people with information to initiate manual energy saving strategies including control of pneumatics, steam or hydraulic systems.
 
All Things PROFINET
 
The organization launched the www.allthingsprofinet.com website to make it easier to find information. The site features a clever layout that starts with selecting your interest as a user, OEM, or device manufacturer. Based on your identity, you are guided to the appropriate information. The user path, for example, has information sub-paths for control engineers, information technology, installer, maintainer, and plant manager. The site includes guides for design, installation, commissioning, maintaining, and cyber security.
 
Wireless
 
Henning told me one of his pet peeves about wireless is people think it is one single solution. He thinks of wireless in terms of four categories - backhaul, process instruments like WirelessHART, wireless sensor/actuator networks, and Wi-Fi. Wi-Fi is used as a backbone in PROFINET. PI North America is working with HART and Foundation Fieldbus Foundation within their wireless cooperation team. Henning noted, “That has been going well.” “The goal is to simplify things for users.” 
 
The Wireless Cooperation Team (WCT) was formed by the Fieldbus Foundation, HART Communication Foundation, and Profibus Nutzerorganisation e.V. (PNO) to develop an interface specification and compliance guidelines to integrate a universally accepted wireless solution into the HART™, FOUNDATION™ fieldbus, PROFIBUS and PROFINET communications networks. The common interface is intended to make it easier for automation end-users to take advantage of evolving wireless technologies. 
 
Early next year the group should have a specification released for Wireless Sensor/Actuator Networks. Henning elaborated, “There is a difference in requirements for discrete and process wireless networks which is why we are doing a separated activity.” At one time they planned a wireless PA specification but when WirelessHART came out they decided it did not make sense and started the cooperation. The reason for a separate discrete wireless network is that process requires slower response times while discrete needs milliseconds response, such as in material handling applications. This wireless sensor/actuator network will use the IO-Link protocol and the WISA technology developed by ABB that is now an open standard.  
 
IT & Automation
 
I asked Henning about his perception about the relationship between automation and IT people. He noted that at every PROFINET training class, they ask attendees about their background and typically there are a couple of IT people.   A couple of years ago at a training seminar, one company related that anything having to do with the automation network had to go through the IT organization including Profibus! Henning feels the tension is still there and he says, “Both sides are the poorer for it.” “There is too much in common and too many benefits to the company if they cooperate; this does not mean they need to be in the same department which could create other problems.”
 
PROFINET for Process Control
 
Henning noted that a new PROFINET for process automation profile is coming soon that makes PROFINET more suitable for process control applications.   This will include proxy devices for Profibus PA, Foundation Fieldbus, and HART, plus time stamping of data, redundancy for controller hot standby, and configuration/run for continuous process.
 
PROFINET Chips
 
The number of suppliers for PROFINET chips is expanding to include NEC, Hilscher, Innovasic Semiconductor, Freescale, and Renesas Electronics Corporation.
 
Thoughts & Observations
 
The PI North America team is always working to improve the information available to help users do things more easily.   The organization of the new all things PROFINET website illustrates an understanding of user needs and problems. www.allthingsprofinet.com
 
The Wireless Cooperation Team participation is a mature approach to the convergence of technologies. That is so refreshing!
 
I am always impressed that PROFIBUS and PROFINET technology are continually being refined. The organization currently has more than 50 Working Groups with over 500 people involved. More information on working groups.
 
The new PROFINET for process automation profile is setting the stage for a battle for open architecture process control system network backbones. Rockwell Automation is promoting EtherNet/IP as the backbone for their process control solutions for new applications and DCS replacements/upgrades. Most process sensor and actuator companies are supporting multiple open networks. Hopefully, the users will be the winners.