Why I Stopped Buying the Cheapest PLC (And Why You Should Too)

The Cheapest PLC Costs the Most. Period.

I've handled procurement for a mid-sized packaging automation company for about seven years now. When I started, my boss gave me one directive: get the lowest price on everything, especially the Mitsubishi PLCs. It sounded simple. It was, in fact, a disaster. People think a low purchase price equals savings. What I mean is, the purchase price is just the entry fee. After tracking $180,000 in cumulative spending across six years in our ERP system, I can tell you the cheapest PLC—even a genuine Mitsubishi unit—is almost always a trap.

The 'Cheap' Vendor's Hidden Tax

In Q2 2024, we needed five Mitsubishi FX5U-32MT/ES units. Vendor A quoted $285 per unit. Vendor B quoted $265. I almost went with B until I calculated the total cost. Vendor B charged for programming cable separately ($45), their tech support charged per-incident ($75 per call), and their shipping added a $30 'handling fee.'

For five units, that adds $150 in hidden fees. Vendor A's $285 price included a cable, free email support, and free shipping. That's a 7.5% difference hidden in fine print. Simple.

Then there's Vendor C, who quoted $240. I should add that they were a grey-market distributor. The savings vanished when the first unit failed to connect to GX Works3—the firmware was two revisions out of date. (Not that they told us that.) We spent four hours debugging what turned out to be a counterfeit chip. That 'cheap' $240 unit cost us $480 in labor. (Which, honestly, made me furious.)

Why Mitsubishi PLC Modbus Integration Can Break Your Budget

Here's a misconception: all Mitsubishi PLCs are the same. Actually, the Modbus implementation varies significantly between series. The assumption is that a cheap FX1S can do what an FX5U does. The reality is the FX1S doesn't support Modbus TCP out of the box. You need an add-on module. That module costs $180. People think the FX1S is a bargain at $150. Actually, to do the Modbus job, the total is $330. A base FX5U that supports Modbus TCP natively is $285.

Switching to the FX5U for our new conveyor line cut our integration time from 5 days to 1.5 days. The automated system eliminated the manual K-map configuration we used to do. That's not an opinion—it's a tracked data point from our engineering log.

How to Test a Battery with a Multimeter (The Cost-Cutter's Way)

This is a small thing, but it saves thousands. During a panic shutdown last October, our maintenance team wasted two hours replacing a perfectly good Centech battery charger because no one tested the backup battery. Here's the method I taught them: set your multimeter to DC voltage. A healthy lead-acid battery (like those in the Linak battery charger units) reads 12.6V or higher. Below 12.4V? It's sulfating. Below 12.0V? It's done. Test under load (press the test button or connect a small 12V lamp). If the voltage drops below 11.0V under load, your battery is dead.

Best part of systematizing this: no more 3 AM panic calls about 'dead' chargers. Also, it saved us $1,200 in unnecessary replacement parts last year. (Should mention: we track every part failure in our CMMS system since 2021.)

Re-Vendoring Your Control System: What the Sales Reps Don't Say

"The value of guaranteed compatibility isn't just the parts—it's the certainty. For a multi-axis control system, knowing your Mitsubishi PLC will talk to your servo drives without three days of debugging is often worth more than a 10% discount from an unknown vendor."

We considered re-vendoring our entire line to a cheaper PLC brand (not Mitsubishi). We gathered quotes. The vendor (let's call them Vendor D) promised 20% savings. What I mean is, the hardware was cheaper. The integrator costs, the software re-licensing, the downtime—I built a TCO spreadsheet. Over three years, the 'cheaper' system would cost us $8,400 more. (Surprise, surprise.)

You're Probably Overpaying for Your Battery Charger, Too

We use Centech and Linak battery chargers for our automated guided vehicles. A common mistake: ordering the 'standard' unit for every application. For a heavy-duty AGV running 24/7, a standard Centech charger will fail in 18 months. The heavy-duty version costs 30% more but lasts 4 years. The cheap option cost us $1,200 in redo costs when a charger died mid-shift.

Our procurement policy now requires a 3-year TCO calculation for any power component over $200. We cut battery-related downtime by 40% in the first year.

The Bottom Line

People will argue that budgets are tight, and you buy what fits today's PO. I get it. But the assumption that a low price is the only metric for cost control is costing companies real money. The causation runs the other way: the vendors who deliver quality and compatibility can charge a fair price because they save you money in the long run. Get the cheapest PLC? Fine. But get ready to pay for the difference twice. Once to Vendor B, and once to your maintenance team for sorting out the mess. Period.

(Cost data as of January 2025. Prices verified via current distributor quotes and internal procurement records.)