If you have ever been on a process or power plant during commissioning or in case of a fault, you have probably asked yourself how to simplify wiring in process-related applications. In these industrial segments, engineers often encounter complex structures and are confronted with long signal paths. Individual subsystems, equipped with local programmable logic controllers (PLCs) or remote terminal units (RTUs), are usually connected via bus systems to the control room and SCADA system, whereby diagnostic tools are available for this network.
The fun starts with troubleshooting on the subsystem level. The individual sensors and actuators are still very often wired with copper in the traditional manner. This means that there are thick cable bundles in cable ducts, and the individual conductors at the cable ends must be terminated correctly and securely. Special care must be taken with analog signals, as a missing or incorrectly connected shield can also cause signal or measurement errors. Troubleshooting under these conditions can be very nerve-wracking (if all eyes are on you) and expensive (production or power downtime).
There are some markets where there are both strong automotive and process industries. Engineers who change sides are bringing alternative field wiring approaches, such as ASi and IO-Link with them. Since these technicians are familiar with the advantages of commissioning and troubleshooting in the production line, they have no reservations about implementation. So let’s take a look at the other side:
In the past in factory automation, parallel wiring has been used.
As product life-cycles are getting shorter and availability has to be high, there is a greater need for modular systems.
Therefore on the sensor/actor level, they are implementing IO-Link more and more, which some people already call the USB port of automation systems. Some advantages of IO-Link include:
- Flexibility in connecting to a wide variety of devices through the same M12 connector. The unshielded cable and robust digital signal effectively conquer issues such as line interference and overcome flexing or bending restrictions
- Digitized analog values (from 4-20 mA, 0-10 V, PT100/1000, thermocouple Type J/K) instead of analog signals
- Additional diagnostic information directly from hubs and sensors/actuators
- Possibility to adapt the host bus system to other countries or customer demands. Only the master module has to be exchanged (most of the wiring diagram will stay the same)
This interesting technical report by Andritz Hydro (Austria) shows how IO-Link was successfully implemented in a hydro power project: “Powering Africa”! (more information about IO-Link solutions).