I/O in the era of Industry 4.0
Control Engineering Europe finds out about I/O device developments which ensures they are prepared to work as part of a digital enterprise.
The role of industrial I/O devices has always constantly changed because industry is constantly changing. Years ago there were only a small number of proprietary protocols; these were superseded by open protocols; and today Ethernet is increasing finding favour within the industrial sector.
“Despite the increasing popularity of Industrial Ethernet it is far from being a magic bullet,” said Derek Lane, automation manager at Wago. “Indeed it is unlikely that there will ever be just one single standard for industrial automation, not only because of the wide range of competing protocols available on the market, but also because every business requires different features from their I/O.
“Ethernet, for example, may be faster over short distances, but transmitting signals anywhere over 100m will require additional boosting. There are, however, some fieldbuses that can transmit over cable runs up to 1,200m without any signal degradation, so the idea of a unified I/O standard is still arguably some years away.”
Process automation architecture has, traditionally, involved a single large master controller governing sequencing, motion and I/O. However, such systems can make changing lines, or increasing and decreasing capacity laborious and with the need for production lines today increasingly having to turn around smaller batches in a shorter timescale, the need for more automated solutions are clear.
According to Lane, a good solution to meet the need for greater production line flexibility is the use of distributed control – also known as modular automation – which relies on smaller, more cost-effective controllers to subdivide tasks into more manageable modules. These modules are equipped with their own intelligence to carry out tasks with less reliance on the master controller, and parts of the process can be changed or adapted without affecting others around them. “Spreading intelligent devices throughout the plant allows more data to be sent back to the control room, which can facilitate more effective predictive maintenance, and provide more opportunities to optimise. This is the essence of Industry 4.0,” said Lane.
This solution allows parts of the production line to be run slower to reduce energy use, or faster to mitigate bottlenecks, without the need for lengthy reprogramming of the whole production sequence. The use of intelligent I/O allows for smarter, more agile processes that can communicate process and device data not only to the control room, but to other devices within the plant. Lane also issued a note of warning: “New technology capabilities also produce new challenges and more and more devices are now using the cloud, which will be problematic if it becomes inaccessible for any reason. Security also becomes more of an issue. The next generation of intelligent devices might open up vast new opportunities for productivity, efficiency and reliability, but for now there is still a place for hard wired, closed loop systems,” he said.
Fit for purpose
Distributed I/O is used to obtain vital data from the industrial shop floor and current innovations are being targeted at making them fit for the increasing demands brought about by the digital enterprise, said Alexander Kessler, marketing for I/O products at Siemens Process Industries and Drives.
“Because automation in a digital enterprise needs to be able to organise and optimise itself, devices must possess intelligence and an absolutely transparent information-seeking behaviour,” he said. Remote I/Os record measurement data and forward signals from automation systems to actuators. Speed and flexibility are necessary to achieve the highest possible transparency of the machine and plant condition – with regard to diagnostic, energy and quality data. “Added to this requirement is an increasing demand for measurement technology, especially when it comes to analogue measurement transducers for the collection of better quality data. At the same time, the integration of intelligent sensors, for example via IO-Link, is gaining importance,” continues Kessler.
“The integration of work steps along the value chain is intended to support the user during the engineering, diagnosis and maintenance – whether this be to avoid wiring errors or to centrally allocate network addresses. The fault diagnosis of the I/Os must allow for an immediate correction of possible errors. At best, the production needs to be able to continue to run.”
The SIMATIC ET 200 distributed I/O is said to help ensure plant transparency, aided by detailed diagnostic, parameter and identification and maintenance (I&M)) data, plant conditions can be retrieved completely virtually. Most ET 200 systems also feature IO-Link master modules for the connection of corresponding sensors and actuators. This creates greater transparency closer to the sensor. In addition to modules for acquiring energy data, modules for high-frequency sampling of analogue and digital signals, also with automatic scaling function, are available.
Plant transparency is also a prerequisite for the seamless integration and digitalisation of the entire value chain. If a perfect digital copy – a digital twin – of product and production can be created, it is possible to run simulations, tests and optimisations in a completely virtual environment, which greatly reduces commissioning times of physical production and so helps to speed up times-to-market. Flexibility, efficiency and quality can be increased while in operation – a necessity to fulfill increasingly individual customer requirements.
“With speed and precision being important metrological requirements in the digital enterprise more analogue terminals with higher measurement rates and resolutions are now required. The ET 200MP and ET 200SP distributed I/Os includes modules with fast sampling rates and high resolutions, making very low fault tolerances possible,” continued Kessler.
For very fast controls, a high-speed interface module with short delay times was developed. With just the isochronous mode it is possible to capture I/O data simultaneously and network-wide, almost without jitter. The ET 200SP high-speed interface module has a cycle time of 125 µs and can be used for very fast and precise control tasks, such as the control of hydraulic presses. In conjunction with a corresponding controller, quick evaluation of quality data is possible.
“Today data from the field required for Industry 4.0 applications are processed in the controller. In the future, it is conceivable that measurement values and data not needed for the actual production process will be forwarded directly to the cloud for processing.
“Several possibilities for this scenario already exist,” continued Kessler. SIMATIC S7-1500 controllers, for example, can send data directly to MindSphere, a cloud-based, open IoT operating system. Routers and gateways for this purpose are also directly to higher-level IT systems or the cloud.
Data exchange in the field
The production chains of factory automation are usually made up of dvices from different manufacturers. “Until recently the data transfer between the machinery in this type of line has often been implemented with an I/O coupling and restricted to a few bits,” said Olaf Ophoff, director product management Factory Automation Systems at Turck. “However, the move towards smart and predictive production chains has required the machinery, and therefore the controllers, to exchange more information between each other than simple ’product ready to transfer’ or ‘transfer station ready to receive’ messages.
“Operators often use an identification system for the data transfer that is based on barcodes or RFID. However, for many product types this is too expensive and simply not possible. Conventional Ethernet gateways with IP20 protection are used when the two machines to be connected use controllers with the same Ethernet protocol. These have to be wired into the control cabinet and therefore require long cabling runs.”
A new I/O block module with protection to IP67 has been developed by Turck to enable data exchange for the first time between two Ethernet networks directly in the field without the need for a control cabinet. The robust TBEN-L spanner is an robust IP67-rated block I/O module which replaces the last I/O module of a machine and functions as a first slave for the next controller in a production line. Compared with conventional IP20 Ethernet gateway solutions, this can reduce costs and wiring effort.
“With this product we are taking one more step out of the control cabinet into the field and enabling data transmission for intelligent production processes, even beyond the limits of individual Ethernet networks,” said Ophoff, “There is also a time saving benefit when the machine is set up at the customer. Instead of running several individual cables to the control cabinet, it is normally only necessary with fieldbus or Ethernet systems to run one communication cable and power supply in order to connect the I/O level to the controller. The wiring of the periphery to the remote I/O technology can then be done in advance at the machine builder and so will consistently reflect the procedures of modular machine building. In addition to the I/O technology, Turck also offers IP67 PLC control technology.”
“Turck is consistently taking the decentralisation further away from the control cabinet into the field,” continued Ophoff. Because the TBEN-L spanner exchanges data bidirectionally from master to master it does not require a control cabinet. Data exchange is therefore carried out where the action takes place – directly in the field where the machines are connected. The spanner acts as a slave for both controllers and thus enables direct master-master communication. The data moves with the product via the spanner from one machine to the next. This enables the signal and data flow to be branched in the production lines – fully in line with the principles of Industry 4.0.
“Turck is consistently taking the decentralisation further away from the control cabinet into the field, Continued Ophoff. Because the TBEN-L spanner exchanges data bi-directionally from master to master it does not require a control cabinet. Data exchange is therefore carried out where the action takes place – directly in the field where the machines are connected. The spanner acts as a slave for both controllers and thus enables direct master-master communication. The data moves with the product via the spanner from one machine to the next. This enables the signal and data flow to be branched in the production lines – fully in line with the principles of Industry 4.0.
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