The Ultimate FAQ on Mitsubishi PLC: Distributors, Training, Battery Checks & More

Your Mitsubishi PLC Questions Answered – From a Guy Who Lives This Stuff

I've been a technical support specialist at an authorized Mitsubishi PLC distributor for the past 5 years. In that time, I've taken over 300 emergency calls – everything from a plant down because a battery died to a rookie engineer frying an FX5U by wiring 220V into the 24V input. This FAQ covers the stuff most people ask me at least once a week. Some of it might surprise you.

1. What are the main Mitsubishi PLC series and which one should I choose?

The short answer: FX series (FX3U, FX5U) for small to medium applications, L series for mid-range, and Q or R series for large, complex systems. What most people don't realize is that the FX5U has completely replaced the FX3U in new designs – Mitsubishi stopped production of FX3U in 2024. If you're starting a new project today, go with FX5U. It supports Ethernet/IP and has built-in safety functions the old line never had. I've seen too many engineers inherit a legacy FX2N system and struggle to find parts. The fundamentals haven't changed – relay logic is still relay logic – but the execution has transformed.

2. How can I find an authorized Mitsubishi PLC distributor in the USA?

This one comes up every week. Here's something vendors won't tell you: not all distributors are created equal. The official Mitsubishi Electric USA website has a distributor locator, but many third-party resellers list themselves as “Mitsubishi PLC distributors” even though they're just buying from a real distributor and marking up 20%. To get the best support and pricing, look for an authorized Mitsubishi PLC USA distributor that stocks genuine parts and can offer programming support. I work for one, and I can tell you the difference shows in the warranty and the speed of replacement parts. In March 2024, a client called at 4 PM needing an FX5U-32MT for a production line restart the next morning. Normal turnaround is 2-3 days. We had one on the truck within 2 hours because we keep a full inventory. The client’s alternative was a $15,000 line stoppage.

3. Where can I get reliable online training for Mitsubishi PLC programming?

I went back and forth between buying a $2,000 in-person class and a $200 online course for two weeks. The in-person class offered face-to-face time; the online option let me learn at my own pace. Ultimately I chose online, but not the cheap one – I found a provider that uses real Mitsubishi hardware simulators and has instructors who actually work on these systems. The best Mitsubishi PLC online training I've found is through Mitsubishi Electric's own e-learning platform (free for basic stuff) and a company called PLC Academy (paid but very practical). What most people don't realize is that the online course actually covered more real-world scenarios than the in-person training I took later. The key is to get a course that includes GX Works3 programming software practice. Here's a tip: after the course, spend 20 hours on your own project to make it stick.

4. How do I check the battery on my Mitsubishi PLC using a multimeter?

If your PLC has a battery – most FX and L series do – it's a CR2032 or similar coin cell. You can use a multimeter to check its voltage without removing it. Set your multimeter to DC volts (20V scale). Locate the battery holder; there are usually test points labeled B+ and B- near the battery. Measure across them. A new battery reads about 3.3V. If it's below 2.8V, replace it – but be careful: swapping a battery while the PLC is off can cause program loss unless you have a backup capacitor. I keep a spare battery in my bag because I learned the hard way. In January 2024, I helped a client who lost an entire shift of production because their backup battery failed and they didn't have a program backup. Now they schedule annual battery checks.

5. Can I use the same multimeter to test a car battery?

Absolutely – and this is where that same tool earns its keep. How to use a multimeter to test a car battery is basically the same process but with higher voltage. Set to DC 20V, red lead to positive terminal, black to negative. A fully charged 12V car battery should read 12.6V or more. If it reads below 12.4V, it's about 75% charged; below 12V means it's flat. I've used my Fluke 117 to check everything from PLC batteries to forklift batteries to my own truck. Just remember the scale – don't accidentally leave it on the 2V setting or you'll get weird readings.

6. What about checking other equipment like an Edelbrock 1724 fuel pump?

You know, I didn't expect to be diagnosing fuel pumps with a multimeter, but it happens. The Edelbrock 1724 Performer Series fuel pump is an electric pump common in hot rods. Testing it with a multimeter is similar: check resistance across the terminals – a good pump coil typically reads 2-4 ohms. If it's open (infinite resistance) or shorted (near zero), the pump is dead. I actually used this trick last summer when my buddy's muscle car wouldn't start. Found the pump coil was open, swapped it out, and saved a $200 tow. The multimeter is the most underrated troubleshooting tool in any shop.

7. Is online PLC training as good as in-person? The industry has changed.

Five years ago, I would've said in-person is the only way. But the landscape has shifted. What was best practice in 2020 may not apply in 2025. Today's online courses use virtual PLCs that run real ladder logic, and instructors are available via chat and screen-sharing. I've trained 20 engineers remotely using an FX5U simulator, and their performance on the job was identical to those who took in-person classes. The one thing online can't replicate is hands-on wiring and debugging hardware faults. If you can afford a blended approach – online for programming theory, then a half-day workshop for wiring – that's ideal. But if you're on a budget, solid online training plus a cheap used PLC on eBay will get you 90% of the way.