Choose the right system architecture – save costs, stay flexible
In industrial automation, choosing the right system architecture determines efficiency and costs and provides scope for future development. Smart communication between the PLC and automation components such as drives, sensors and valve terminals can not only significantly reduce overall costs, but also ensure the flexibility and expandability of a system. Today, users have a wide range of design options at their disposal: from discrete wiring and fieldbus systems with Remote I/O to centralized and decentralized pneumatic connections. In this blog post, we take a look at the areas of application, advantages and disadvantages of the various architectural approaches with a focus on costs and flexibility.
Discrete wiring: Cost-effective solution for small machines
With discrete wiring, each individual component, such as sensors and actuators, is connected directly to the central control unit in the control cabinet. Each input and output requires its own line. Although this eliminates the need for expensive and complex communication protocols and bus nodes, the architecture quickly reaches its limits and, with increasing size, leads to high cabling costs and takes up a lot of space in the control cabinet. The system quickly becomes extremely complex and error-prone when expansions are made. However, this system is sufficient for small machines or systems with manageable inputs and outputs, as long as costs and space requirements are kept within limits.
Fieldbus systems: For relatively complex automation tasks
Fieldbus systems are digital networks that connect several devices to the control unit via a single communication line. Examples are ProfiNET, EtherNET/IP or EtherCAT. These are relevant for medium to large systems with a large number of inputs and outputs. This is because a fieldbus significantly increases the flexibility and scalability of a system: fewer cable lines are required, as a single data line now reduces the number of discrete connections. New devices can be easily integrated into the network and different components can communicate via the same bus. Diagnostics are also made easier, as faults can now be identified more easily.
At the same time, the necessary fieldbus nodes are very cost-intensive and compatibility is becoming an important issue: after all, not every device can communicate with every fieldbus. The architecture is dependent on the fieldbus protocol used in the PLC.
Remote I/O: Out of the control cabinet
Remote I/O relocates I/O modules from protection class IP65 to remote locations close to sensors and actuators. These modules communicate with the central control system via fieldbus systems. Remote I/O is essential for large and extensive systems if the modules are to be placed outside the control cabinet and close to the components. The wiring effort is further minimized, the data rates increased and the control cabinet capacity significantly reduced. Installation on the plant floor also makes it much easier and cheaper to scale the machine while simplifying servicing, because faults can be diagnosed and rectified directly on site.
The use of Remote I/O has become an integral part of modern automation architecture and represents a major benefit for automation. However, this technology is initially the most expensive to purchase. The system is much more dependent on a stable network connection and requires a great deal of expertise in planning and integration.
Pneumatics and electrical automation perfectly connected
The integration of valve terminals and pneumatic components into an automation system offers great potential, but also harbors the risk of oversizing due to long and complex tubing, and high costs due to additional interfaces being required. However, with the right components and a communication language that is as uniform as possible, a decentralized or hybrid (modular and decentralized) connection can be implemented. This reduces the number of bus nodes and IP addresses while simplifying diagnostics.
