If you're comparing Siemens PLCs by unit price, you're making a mistake. I'll say it plainly: the unit price is the least interesting number on the quote.
I've spent the last six years managing procurement for an 80-person systems integrator. We buy Siemens PLCs almost every month, from S7-1200 CPUs to S7-1500 I/O modules. I manage roughly $400,000 a year in automation component purchases and track every invoice in a cost model—freight, setup, training, support, rework, downtime—and the pattern is hard to ignore. The lowest quote rarely becomes the lowest total cost.
I'm not a Siemens engineer, so I can't walk you through configuring the 6ES7193-6AG20-0AA0 in TIA Portal. But I've approved enough orders to know where the money actually goes. And that's the perspective I want to share.
Most buyers focus on the CPU price and completely miss everything that turns a PLC into a working control system. The 24V power supply, signal modules, terminal blocks, DIN rail, software, engineering time, HMI integration, testing, documentation, spare parts, and training. None of those are free. They're just not always on the quote.
The question everyone asks is "What's your best price?" The question they should ask is "What's included in that price?"
Three years ago, we accepted a quote that came in $1,400 below the nearest supplier. It didn't include freight, a minimum order charge, or the fact that the material would arrive in three different shipments. By the time we added the extra fees and the hours spent tracking the boxes, the saving was maybe $230. Then the firmware didn't match our test environment, and we lost two days of commissioning. The order we thought was cheap ended up being the most expensive one we booked that quarter.
I built the TCO model after getting burned on hidden fees more than once. It includes hardware, software, engineering, skills, support, logistics, and risk. Risk is the big one. A failed startup or a downtime event can add more cost than all the other categories combined. Siemens also publishes security guidance around IEC 62443; whether you need it depends on your plant. The point is, that kind of requirement is part of TCO, not an optional extra.
Think about the searches people type when they're being proactive. "How often should I change my home air filter?" is not exciting, but it prevents an expensive HVAC repair. "Power washer spark plug" is the same story: a small part replaced on schedule keeps a piece of equipment starting when you need it.
PLCs work exactly that way. A spare signal module or a spare CPU looks like dead inventory until a production line stops and the only choices are overnight freight, overtime labor, and a long uncomfortable conversation with plant management. That's why I now treat spare parts and Siemens PLC online training as normal line items in every project, not as emergency expenses.
Search for "Siemens 6ES7193-6AG20-0AA0 PLC direct" and you'll get a price and a buy button. That part number is a component in a bigger configuration, not a complete control system. I will not pretend to know every pinout from memory—this is where my professional boundary is. But from procurement, I can tell you that buying a line item without checking compatibility, firmware, and lead time is a red flag.
To be fair, direct part-number ordering is fine when you know exactly what you need. I order spares that way all the time. But for a new machine or a less familiar configuration, it's not a project plan.
The Siemens Industry Online Support portal is the authoritative place to verify spare part status, firmware versions, and compatibility. Use it before you order, not after. If you're working with an integrator, their configurator should be part of the process. Those checks cost time, and that time is part of the real price.
The best Siemens PLC price in the world won't program itself. TIA Portal is a powerful environment with a serious learning curve. If your team is new to the platform, a Siemens PLC online training course belongs in the project budget, not in the "maybe later" column.
Search for "PLC programming for beginners" and you'll find endless options. That's not the problem. The problem is that companies buy the hardware before they buy the skill. I've watched a commissioning engineer burn days on something an experienced Siemens programmer would have solved in an hour. Those days show up in the project cost, even though they never appear on the hardware quote.
One of the smartest purchases we made was a structured online training program plus one spare CPU. It sounds like a luxury. It isn't. In most cases, that is a no-brainer. It's the same logic as keeping a spare filter in the closet or a spare spark plug in the toolbox.
I hear the objection: "We don't have money for training and spares. We need the lowest number." I get it. I'm the one who defends budgets in procurement reviews. But TCO is not an excuse to spend more. It's a reason to spend better. If you have to cut, cut scope. Don't cut the skill. Buy the standard CPU, but keep the spare module. Skip the premium panel, not the training.
There's also the old belief that Siemens is expensive. That idea comes from an era when hardware was the biggest line item on the project. In today's automation world, engineering, commissioning, security, and downtime usually dwarf the hardware premium. I'll take a well-supported, well-trained project over a slightly cheaper box every time.
Bottom line: I still compare prices. I'd be foolish not to. But I compare them with a TCO calculator, not a gut feeling. The best Siemens PLC purchase is not the one with the lowest list price. It's the one that arrives on time, works the first time, and keeps working after the original engineer has moved on.
There's something satisfying about a PLC project that starts up without drama. After you've chased enough hidden costs, you learn to buy for that moment.
So stop comparing unit prices. Start comparing total costs. That single change will improve your next PLC purchase more than any discount you can negotiate.