PLCs are Underrated

Here's a fun game you can play with industrial automation startup founders: ask them how their UL certification process is going. You may see three different responses. (1. Technically four: they may respond with "huh?" in which case you should leave them alone. They are probably not building anything serious. )

For context, OSHA requires most equipment used in an industrial setting to be certified by a Nationally Recognized Testing Laboratory (NRTL). This means—among other things—making sure it won't maim someone or spontaneously catch fire. The process can be costly and time consuming, depending on the complexity of the equipment.

The brainlet wojak at the left end of the bell curve is using Programmable Logic Controllers (PLCs) to drive their automation. These are tough, simple little computers that map inputs to outputs in a way that mimics relay logic from old factories. Most automation technicians will be trained on PLCs, often through a vocational college instead of a four-year degree. They are designed to be very simple.

Our crying wojak in the middle has rolled their own solution. His team is simply moving too fast, and an antiquated PLC will not have the compute to keep up, he says. His EE's have been trained to build PCBs, his firmware engineers prefer to write C, and his mechE's keep changing the sensors and actuators. Many people are kept gainfully employed (#reindustrialize!), and everyone feels very productive, but the hammer comes down when they try to certify their hardware. All those wonderful idiosyncrasies have to get ironed out as consultants rack up billable hours. Nightmare!

At the right end of the bell curve, our wizard wojak has understood The Way.

Lack of constraints is bondage to decisions. Embrace of constraints is freedom to experiment. Our wizard engineer spends his innovation points (2. Known in the biz as "mana." ) wisely by picking simple, reliable technologies for the majority of the project. He cuts at the joint, leaving control to the controllers and compute to the computers—these can be connected over a fieldbus with microsecond-level latency. And certification is much easier, since his control panel is entirely made of UL-listed parts.

There are, of course, some cases where a PLC would be inappropriate. But for simple motion control, driving relays, reading sensors, i.e. the majority of what goes on in industrial automation, you should really consider whether you need to roll your own hardware. Use more PLCs!