AppMarsh readers don’t want an advent to the Arduino. However in commercial keep watch over packages, programmable common sense controllers or PLCs are way more not unusual. Those are small rugged units that may do easy such things as observe switches and keep watch over actuators. Being ruggedized, they’re in most cases relatively dear, particularly in comparison to an Arduino. [Doug Reneker] determined to^( in a reasonably easy industrial-style utility.
The applying is a straightforward closed-loop keep watch over of go with the flow generated by way of a pump. A sensor measures go with the flow for the Arduino, which adjusts a keep watch over valve actuator to deal with the required setpoint. The device makes use of proportional and integral keep watch over (the PI a part of a PID loop).
Even though the Arduino has a sensible choice of I/O pins, it doesn’t have not unusual I/O features you’d be expecting in an commercial controller. For instance, the go with the flow meter used within the demo produces a present proportional to go with the flow starting from 4 mA to 20 mA. That’s a quite common arrange in an commercial tool since present loops are ready to care for lengthy cord runs, in conjunction with different causes. [Doug] discovered he needed to create a converter to get the knowledge to the Arduino. He additionally wanted a approach to convert the Arduino’s PWM output to a 4-20 mA output, which was once much more sophisticated.
After all, the PLC had all of those choices already, in conjunction with a consumer interface appropriate to the duty. From that [Doug] drew the realization that whilst the elemental was once less expensive, it was once a wash by the point you added the ancillary parts. He additionally felt that the engineering time to construct the Arduino model of the mission swamped the entire prices of the usage of the PLC.
Usually, we don’t disagree. Alternatively, it relies on what you are attempting to perform. Whilst a hammer is excellent at riding nails, it isn’t excellent with screws. You wish to have the correct device for the activity. When you actually had 4-20 mA equipment and wanted a PLC-like consumer interface, then, after all, the PLC is most likely the correct selection. Alternatively, should you had began with the Arduino, it’s good to have decided on higher go with the flow tracking and actuator alternatives, supplied higher energy, and used a consumer interface extra fitted to the Arduino and gotten a greater outcome.
Don’t get us flawed. PLCs have a spot. So do Arduinos. So do ARM chips, Raspberry PIs, and 555 timers. For [Doug’s] mission a PLC was once obviously the correct resolution. That doesn’t imply it’s all the time the correct resolution. Alternatively, we did suppose seeing the comparability between the two would possibly assist PLC mavens perceive the Arduino higher and vice versa.
Even though maximum PLCs are proprietary, we’ve lined^( . Perhaps the most efficient thought isn’t to pick out one or the opposite, however ^( .
Filed beneath: Arduino Hacks