Electricity and Control July 2021

CONTROL SYSTEMS + AUTOMATION

Universal I/O systems satisfy a wide range of requirements. However, the resulting advantages go to waste if the necessary interface and marshalling level cannot be designed just as flexibly.TheVIP I/O marshalling system ensures a high degree of flexibility. Flexible I/O marshalling system in process automation Felix Schulte, MSc, Global Program Manager, Phoenix Contact Electronics GmbH

Felix Schulte, Phoenix Contact Electronics.

T he basic structure of signal marshalling – the sorting and combining of field signals and their connection to the I/O system – necessary within the framework of process automation, has not changed for a number of years. The rigid system structures, resultant high planning outlay and considerable installation and commissioning costs regularly lead to project delays and increased overall costs. This is the case for new systems and the modernisation or extension of existing applications. System operators have therefore been placing specific demands on planners and suppliers for quite some time. For example, the systems must be able to respond flexibly to changes; design dependencies should be eliminated; and the systems should allow for greater focus on key design decisions. In this article we look at the existing problems, how planners and suppliers have already responded to these three framework conditions, and the advantages of Phoenix Contact’s flexible VIP I/O marshalling system in this context. Tailored signal conditioning In response to the operating ideals noted above, pioneering manufacturers of distributed control systems introduced universal I/O systems several years ago. Since then, this concept has become established on the market under various brand names. The difference between classic I/O systems and universal solutions is, as the name implies, the new I/O systems are versatile in application. This means the individual I/O channels can be adapted to the necessary

The classic configuration of a processing system comprises field distribution boxes and marshalling, interface, and control cabinets. 16, or 32 channels – for example, 16-channel input cards for analogue signals or 32-channel output cards for digital signals. In contrast to this, universal I/O cards open up the possibility of adapting each channel individually. For example, the first three channels of a 32-channel card can be configured as analogue inputs, the next five channels as digital outputs, the next channel as a digital input, and so on. At first glance, this appears to be a small measure, but it is of particular benefit when planning and realising the signal marshalling. Wherever conventional I/O systems are used, the sensor and actuator field signals available in any chosen sequence must be pre-sorted and grouped into blocks so they match the cards used. Moreover, the I/O card types required in such a classic structure can only be determined once it is clear which signals are present in the system and in what quantity. In contrast, universal I/O systems allow planning based just on the total number of I/Os. Initially, the individual functions are not important because the I/Os can be be adapted using software in later stages of the project. This seemingly simple measure also eliminates the need for complex signal marshalling, because each signal circuit is physically identical in structure. Considering the interface technology Thus universal I/O systems meet the system operators’ requirements listed above. Since channels can be reconfigured in any way, the universal solutions provide a flexibility that was not available before. They eliminate design dependencies during the course of the project. For

function via software. Until recently, solutions were made available with each forming signal blocks of 2, 4, 8,

VIP I/O marshalling is a flexible I/O marshalling system for the process industry.

4 Electricity + Control JULY 2021