Jason Haldeman is senior product specialist—I/O and gateways, at Phoenix Contact.
What are the advantages of IO-Link in terms of diagnostics?
Jason Haldeman, senior product specialist—I/O and gateways, Phoenix Contact: Diagnostics is a key feature that drove the development of IO-Link for sensor communications. Before IO-link, sensor diagnostics readable via the control system were nonexistent. Sensors had internal diagnostics but were only able to display this locally at the sensor. IO-Link changed this and now allows the IO-Link I/O module to read diagnostics and back up the sensor configuration for fast sensor replacement.
What cable topology options are available with IO-Link? Can I use daisy-chain connections, or is a dedicated point-to-point connection required for each device?
Jason Haldeman, senior product specialist—I/O and gateways, Phoenix Contact: IO-Link is a point-to-point communications network and was not developed to be daisy-chained. The idea behind IO-Link was to change nothing about the way sensors were wired to the I/O module and find a way to talk to the sensor. Typical sensors need three wires: power, ground and signal. IO-Link simply took the signal line and turned it into a new communication protocol that could be turned on and off as needed. So, in the specification, IO-Link at a minimum simply requires a non-shielded three-wire sensor cable but can also support five-wire cables if additional signal or power lines are needed.
How does IO-Link integrate with different fieldbus protocols commonly used in automation systems?
Jason Haldeman, senior product specialist—I/O and gateways, Phoenix Contact: When looking at IO-Link master, it helps to think of it as just a smart I/O module. On the I/O side, we have the IO-Link communications providing the three key features: sensor data, sensor configuration and sensor diagnostics. On the fieldbus side, the module views the programmable logic controller (PLC) as an I/O module with a lot more data. For example, a traditional Ethernet I/O module with eight digital channels may transmit 2-4 bytes of data to the PLC. Eight bits are for I/O signals, and the rest may be some simple diagnostics bits. For an eight-channel IO-Link master I/O module, each channel can transmit up to 32 bytes plus another 9 bytes for alarm data. So, eight channels may transmit up to 328 bytes of data to the PLC. This extra data can be overwhelming to the programmer, but, in the end, it’s all the data you will ever need. You may only need a few bytes to run the application, and the rest can be funneled through the PLC up to a human-machine interface (HMI) or cloud to be evaluated for predictive maintenance.
What are the cost implications of implementing IO-Link compared to traditional wiring methods? Is the upfront cost of IO-Link devices offset by long-term benefits like reduced wiring complexity and improved diagnostics?
Jason Haldeman, senior product specialist—I/O and gateways, Phoenix Contact: First, if you look from a component cost, moving to IO-Link has a minimal increase in cost. If you also factor in converting analog sensors to IO-Link, the cost will be reduced through the elimination of analog-to-digital (AD) converters. But, like any newer technology, there is an engineering cost that keeps the cost a little higher until the market embraces the technology.
From the customer side, the minimal cost increase can easily be absorbed through the features IO-Link provides, like fast sensor replacement, because the I/O modules—IO-Link master—can back up the sensor configuration. Additionally, the sensor can provide precise diagnostics to prewarn its end of life, allowing the device to be replaced on normal downtime vs. system fault.
Tell us about one of your organization’s state-of-the-art IO-Link offerings.
Jason Haldeman, senior product specialist—I/O and gateways, Phoenix Contact: The TRIO Power 24 V power supply from Phoenix Contact features a space-saving design, easy handling, and smart diagnostic functions.
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