Comparing OMRON NX and CJ Series: What an Admin Buyer Actually Needs to Know
When I first started handling automation component orders back in 2022, one of the most confusing decisions was choosing between OMRON’s NX and CJ series PLCs. Both are solid. Both are widely used. But they’re not interchangeable. So, here’s the thing: I’m not an engineer. I’m the person who actually places the orders, manages the vendors, and makes sure the right part arrives on time without blowing the budget. And when our lead engineer said, “We need either an NX102 or a CJ2M,” my first question was, “How do I even compare these?”
This article is my attempt to lay out that comparison in plain terms. We’ll look at five key dimensions: key advantages, system integration, programming ecosystem, total cost of ownership (TCO), and scenario fit. No fluff, no marketing talk. Just what I’ve learned from ordering both.
Dimension 1: Key Advantages
NX Series (e.g., NX1P2): The Modern Controller
Main draw: It’s newer. The NX series is built on OMRON’s Sysmac platform, meaning tighter integration with IO-Link, safety, and motion control. It’s designed for Industry 4.0—think data connectivity, OPC UA, and EtherCAT built-in. Our engineering team loved that the NX1P2 integrated safety and standard control on one platform, cutting cabinet space by about 20%. (Should mention: we had a compact panel requirement for a new production line, so every inch counted.)
CJ Series (e.g., CJ2M): The Workhorse
Main draw: Reliability, legacy support, and simplicity. The CJ series has been around longer, and it’s still a beast for traditional machine control. It uses the older but extremely robust CX-Programmer software. For our older machines that just run, the CJ2M is plug-and-play. No need to retrain technicians. Cheaper per unit, too.
Conclusion: NX is the future. CJ is the proven present, especially for cost-sensitive or legacy environments.
Dimension 2: System Integration Difficulty
NX Series: Smoother but Stricter
Setting up an NX system means using Sysmac Studio. This is fine—it’s modern, drag-and-drop, and unified. But it also means you can’t mix-and-match old-school modules easily. If your plant runs a mix of older hardware, the NX might require adapters or more complex cabling. For example, the NX-PD series of I/O units works great, but only within the Sysmac ecosystem.
CJ Series: More Flexible, More Legacy
The CJ series uses the older “CJ Bus” and is compatible with a huge range of modules—some from over a decade ago. That makes integration with existing gear much simpler. However, the configuration can be more manual. Our maintenance team spends more time wiring and testing CJ setups compared to the NX.
Conclusion: NX wins for new builds. CJ wins for retrofits or multi-vendor environments.
Dimension 3: Programming Ecosystem
NX Series: Sysmac Studio
Unified environment for logic, safety, motion, and HMI. Modern. Comes with simulation tools. But the license cost is higher. Expect around $1,200 for a basic license (circa 2023).
CJ Series: CX-Programmer
Older but widely known. Many maintenance techs already know it. Less expensive—around $400 for a basic license. However, it lacks safety programming and integrated simulation.
Conclusion: NX is better for in-house engineering teams who want efficiency. CJ is better if you rely on external integrators who already know CX-Programmer.
Dimension 4: Total Cost of Ownership
NX initial cost: Higher. The NX1P2 CPU alone runs $600–$900. A basic starter kit with software and cables can hit $2,500.
CJ initial cost: Lower. A CJ2M CPU is around $400. A comparable starter setup maybe $1,500.
But here’s the catch: total cost of ownership depends on how much integration and maintenance you need. For us, the NX saved about 3 hours per week in troubleshooting and 2 hours in wiring—per machine. Over a year, that’s $4,000–$5,000 in engineering labor savings. So if you have multiple machines or a new line, NX pays back fast.
On the other hand, for a single dedicated machine that runs 4 years with no changes, CJ is cheaper over the lifecycle. Not ideal for scalability, but workable.
Conclusion: NX for volume/scalability. CJ for single-station or legacy applications.
Dimension 5: Cables and Accessories
Now, a practical note: NX uses EtherCAT cables (RJ45). Standard Cat5e or Cat6 works. CJ uses proprietary “CJ Bus” cables, which cost about $30–$50 per cable and require specific connectors. I learned this the hard way—I ordered standard Ethernet cables for a CJ setup, and they didn’t work. The vendor (thankfully) took them back.
Also, for NX, OMRON offers a direct NX-series cable set that’s well-priced. For CJ, you’re often buying from third-party distributors, which introduces lead time risk.
Conclusion: NX wins on cabling simplicity and lower accessory cost.
So, What Should You Choose?
Here’s the framework I use now when our engineers ask:
- Choose NX if: You’re building new equipment. You want modern software. You care about data connectivity and safety integration. You have budget for a higher upfront, and you’ll benefit from lower maintenance costs.
- Choose CJ if: You’re upgrading an existing machine. You have legacy modules. Your team is already trained on CX-Programmer. You need the lowest upfront cost for a single application.
A lesson learned from my own ordering: last year, I found a good price on CJ2M CPUs from a new distributor—about $100 cheaper per unit. I ordered 5 for a retrofit project. But the distributor couldn’t provide proper invoicing (handwritten receipt only). Finance rejected the expense. I had to eat the cost out of my department budget. Now I verify every vendor’s invoicing before ordering even one cable.
That vendor? I don’t use them anymore. The ones who treated my $200 orders with respect back in 2020 when I was starting out are the ones I trust with $20,000 orders today.
This comparison worked for us, but we’re a mid-size B2B company with predictable ordering patterns. If you’re running a high-mix low-volume environment or have heavy reliance on legacy automation, the calculus might be different.
Reference: Industry standard programming languages for PLCs follow IEC 61131-3, covering Ladder, FBD, ST, IL, and SFC. Both OMRON NX and CJ support these, but Sysmac Studio for NX provides a more streamlined implementation. Source: IEC 61131-3, 3rd Edition (2013).
