As industrial infrastructure becomes increasingly distributed, the challenge for system integrators is not simply how to collect more data, but how to do so efficiently. Here, Ian Loudon, international sales and marketing manager at remote monitoring specialist Omniflex, explains how flexible, universal I/O modules are key to overcoming the challenges of traditional fixed-function modules.
A pump station may need to monitor a mix of equipment status, alarms and analogue measurements, while a large industrial site could have thousands of signals dispersed across multiple buildings or plant areas. In both cases, bringing every signal back to a central control station could introduce significant amounts of cabling, while using conventional remote I/O modules can result in hardware that is only partially utilised.
The problem is that most traditional I/O architectures are built around fixed functions. For example, a module dedicated to fixed digital inputs, analogue inputs or outputs. However, this approach quickly becomes inefficient when applications require a mixture of signal types or need to expand over time.
For system integrators, this can mean using several different modules to accommodate a relatively small number of signals. The result can be greater hardware requirements, more panel space and additional wiring even though the underlying requirement is simply to get field data into an existing control or monitoring system.
The challenge of distributed I/O
Industrial operators increasingly need visibility of equipment located across large sites, in separate buildings or at remote points in an installation. The traditional response is often to bring field signals back to a centralised I/O cabinet, but this can require substantial cabling infrastructure.
That approach is not practical or economical for every application. Long cable runs add huge installation costs and can make future modifications more difficult, while the physical infrastructure itself can become a constraint when new monitoring points are required.
Distributed I/O provides an alternative by moving the interface closer to the equipment being monitored and transmitting the information back to the wider control system over a communications network. However, this creates a new challenge around how much hardware is required at each remote location.
If every signal type requires its own dedicated module, the benefits of distributing the I/O can quickly be offset by a proliferation of hardware. A system that is physically distributed may still be unnecessarily complex from an engineering perspective.
The challenges of varying applications
The difficulty is that industrial monitoring requirements are rarely uniform. Even in the same facility, one location might require predominantly digital inputs, another might need analogue measurements, while another could require a combination of inputs and outputs. Requirements can also change as equipment is upgraded or additional monitoring points are introduced, making flexibility increasingly important.
Rather than selecting I/O hardware based on a fixed combination of functions, system integrators can benefit from platforms where individual channels can be configured according to the requirements of the application.
The same principle can also help when expanding an existing system. If additional I/O can be added without replacing the original architecture, operators can extend monitoring incrementally rather than undertaking a major redesign.
Communications are another important consideration because, for integrators, familiarity and interoperability are often just as important as the number of I/O channels available. Where Modbus is already being used in a control or automation system, adding a new I/O platform should be straightforward rather than requiring a separate communications architecture.
A more flexible approach to remote I/O
This is where Omniflex’s Teleterm M1 can help address the requirements of distributed I/O applications. The M1 provides 16 universal I/O channels that can be configured for analogue or digital inputs and outputs. This allows system integrators to create the combination of I/O required for a particular installation rather than having to select separate fixed-function modules for each signal type.
The module can communicate using Modbus/RS485 and operate as either a master or slave. This allows it to be used as an expansion module alongside an existing RTUs or as part of a distributed I/O network and is compatible with all Modbus enabled PLC, DCS, SCADA systems.
The latter approach can be particularly useful where monitoring points are geographically dispersed. Rather than routing every field signal back to a central location, I/O can be positioned closer to the equipment and connected over the communications network. The result is a more modular architecture in which additional monitoring points can be introduced where they are needed.
Putting flexible I/O into practice
The approach is already being applied to distributed alarm monitoring in the nuclear sector. For example, at Sellafield nuclear site, M1 modules have been used as standalone units to collect critical alarms from changing rooms associated with new-build projects. These digital signals are communicated using Modbus into the radiation protection network, where they can be presented as alarms within the wider monitoring system.
The application illustrates the wider value of distributed I/O where the objective is not necessarily to create an entirely new control system, but to provide an efficient interface between field signals and an existing network.
This is an increasingly common requirement as industrial operators expand and modernise their infrastructure. New equipment may need to be incorporated into established control and monitoring architectures, while the cost and disruption associated with running new cabling or replacing existing systems needs to be kept under control.
Flexible I/O can provide a way of addressing that requirement without making the architecture unnecessarily complicated.
Choosing I/O around the application
As industrial monitoring systems become more distributed, there is a case for moving away from the assumption that I/O should be designed around fixed hardware functions.
For system integrators, the more useful starting point is considering the application itself in terms of what signals must be collected, where are they located, how are they going to be communicated and how those might requirements change in the future.
To find out more about the Teleterm M1 and how it could be used in distributed I/O applications, visit Omniflex’s website.
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