By Conal Watterson & Brian Condell
Input-output modules (I/O modules) are often connected locally to the PLC in a control cabinet away from operating equipment, and so are referred to as local I/O modules. Various trends within Smart Manufacturing drive manufacturers to increasingly connect more I/O modules away from the PLC and closer to the action – with remote I/O modules directly alongside field equipment including sensors and actuators. This first blog in this series will discuss the benefits of using remote I/O modules and the key trends influencing their increased adoption across flexible manufacturing.
Why Use Remote I/O Modules?
There are many reasons why a manufacturer may wish to use remote I/O modules over local I/O within the smart factory. Here are some of the key advantages:
- Reduce wiring & distance to sensors – Connecting 4-20 mA loops and digital I/O to a remote I/O unit eliminates a bundle of cabling that would otherwise connect back via a marshaling cabinet to the PLC, in the case of local IO. Instead, segments of just one cable (e.g. 100 Mbps Ethernet or Fieldbus) daisy-chain directly between the control cabinet and remote I/O modules. Install time and cost of cabling are reduced by eliminating the routing of a multitude of individual cables up to 1 km each, all the way back from field instruments (edge nodes) to the control cabinet and PLC via a marshaling cabinet.
See the image below.
This results in reduced installation costs (less wiring, less cable tray required), which in turn leads to faster installation. Since there is now a reduced number of failure points it simplifies troubleshooting. Future project expansion is also eased due to just having to add an additional input output card within the remote I/O enclosure (no need for additional wiring back to the PLC in the control room).
- Simplify control – Connecting remote I/O modules offers an alternative to installing PLCs next to each piece of equipment. One PLC can be connected to remote I/O modules at various locations.
- Connect legacy nodes to Ethernet – The vast majority of factory floors and process industries have established automation systems that are simply added to rather than refitting entirely. At the same time, newer control systems leverage Ethernet-based connectivity to handle larger volumes of data, reliably in real-time. Installing newer remote I/O modules can connect existing field instruments such as those connected with 4-20 mA loops, to Industrial Ethernet networks.
- Control in harsh environments – In some applications, it is not possible to have PLC with local I/O modules near the field devices because of the harsh environment. However, remote I/O modules can be far more rugged and resistant to harsh environmental conditions than a PLC.
Recent Trends Driving Remote I/O Modules
While remote I/O modules have been around for several years, recently there has been a greater demand for not just any remote I/O module, but for next-generation modules that have more to offer manufacturers.
- Digitization – Customers require seamless access to insights available via sensors on the factory floor. This means moving more data, some of which is deterministic and requires real-time control leading to a move to Ethernet and support for multiprotocol.
- Agile Automation – Manufacturers need flexible systems that can quickly and easily adapt to changing requirements, all driven by shifts in consumer behaviors and demand. As a result, they can no longer rely on fixed, large-scale systems designed for mass-market products and predictable demand. Instead, flexible systems that can be reconfigured quickly with minimal downtime and capital investment are required.
- Optimization – One key focus in Factory 4.0, is the use of higher density form factors, reducing cable runs, simplifying troubleshooting, and faster installation.
- Reliability – Reliability and in turn, EMC robustness is a key requirement for many manufacturers today to ensure the maximum uptime of their end equipment.
- Security – Legislative changes such as the EU Cyber Resiliency Act place a burden on manufacturers to ensure the implementation of hardware-based security for their automation equipment/modules.
Future blogs in this series will explore the key benefits that next-generation remote I/O modules have to offer and show where ADI’s technology is helping manufacturers meet the growing trends driving the remote I/O market within factory automation.
Read the next blog here.
