In most industrial applications 80-90% of the I/O going back to the PLC is discrete points. Multiple times I have been asked, “How can I easily, quickly, and cost effectively get one channel of analog back to my PLC”. The solutions in the past have either involved an IP20 slice I/O solution in a J-box, which is expensive and labor intensive, or an IP67 network module, which reduces labor costs but still carries a high cost. A common drawback to these solutions is that you have to pay for 2, 4, or even 8 channels when only one is required.
IO-Link – One solution is IO-Link, an open communication protocol, which allows higher end products to cost effectively and quickly pass their data and parameters through a standard 3-conductor cordset. As IO-Link grows in acceptance, more and more vendors are producing IO-Link Proxy’s/Gateways that allow the IO-Link data to be passed along a network protocol, like; Profibus, ProfiNet, and EtherNet/IP. By building a buffer of unused IO-Link ports/connections into your application, you allow yourself the ability to add an analog sensor that converts the analog signal to digital within itself or a simple IO-Link analog converter that takes any standard analog signal and converts it to digital.
So by adding IO-Link to your application and allowing a buffer of IO-Link connections, the answer to what do I do about “that 1 channel of analog” is simple, cost effective, and fast to implement.