This is the third post inspired by Advantech’s white paper, Industrial Bus & Network Standards. The previous two entries explored the dynamics which favor standardization in general, some obvious and some not, and then the Ethernet standard specifically. This installment will delve into the paper’s revelation of just where the greatest cost of implementation of External I/O lies, and what it indicates for system-design considerations.
Advantech notes that, while Internal I/O connect directly to a controller via an internal bus, External I/O, by definition, connect via some form of external network, usually consisting of wiring, and it is the installation of the physical wiring connecting a controller to an External I/O that typically creates the greatest cost of the overall system. As an extreme example, Advantech notes that installation of wiring in explosion-proof conduit and junctions can cost as much as $3000 per linear foot. Also noted is that the complexity of these physical systems often results in integration of cable concentrators and marshaling cabinets. The expense of such network infrastructure dictates that that External I/O be long-lived since replacement can often require the substitution of its supporting field wiring as well.
Deploying third-party External I/O systems, such as those available from Advantech, offer five distinct advantages:
- Tried-and-true External I/O components are specifically engineered for long service lives, thus mitigating future need to reconfigure existing wired-network architectures;
- Off-the-shelf External I/O components are available with a sufficiently-wide array of features to accommodate existing wiring architectures, simplifying both initial configuration and subsequent reconfiguration as application demands require;
- Dependable External I/O components simplify maintenance and troubleshooting. In the rare event that an external input fails, it is more cost effective to simply replace it – without opening the controller case and exposing it to contamination;
- External I/O components sourced from industry leaders like Advantech are supported by sophisticated software and standardized device drivers, such as Advantech’s Adam/Apax.NET Utility;
- These modern External I/O components are compatible with a variety of legacy controllers as well as with I/O from other manufacturers.
Considering these advantages, it is wise to consider off-the-shelf External I/O solutions from such reliable sources as Advantech when designing and building your physical network.