Evaluating an Automated Cable and Harness Tester for a Rapidly Changing Production Environment
When your cables get returned because the connector was wired backwards — and the manual test missed it too — it's time to rethink the process.
At Konrad Technologies, we design and deliver custom test systems for companies worldwide. Most of these systems ship in small quantities, and nearly all of them require a set of cables or harnesses built to spec. Before any cable goes into a test system, it needs to pass electrical verification — because a wiring fault doesn't just mean a failed test, it can damage the customer's Unit Under Test (UUT). So I set out to evaluate whether an automated cable tester could replace our manual process, improve quality, and maybe even save time. Here's what I found.
The Problem with Probing by Hand
The existing process at Konrad Technologies is straightforward but fragile. A technician grabs a Digital Multi-Meter (DMM), sets it to continuity or resistance mode, and probes each pin on the cable against its intended connection point. They also check for shorts between adjacent or all pins, depending on the project lead's call. Results get written by hand into an Acceptance Testing Record (ATR), which is then scanned and filed.
This works fine on a good day with a simple cable. But the cracks show quickly:
- Inconsistent DMMs. Two meters can read hundreds of milliohms apart on the same wire. Battery level affects readings. Probes "settle" over several seconds before landing on a stable value. When your spec tolerance is tight, this is a real problem.
- Improvised probe tips. Standard DMM probes don't fit most connector cavities, so technicians wrap bare solid-core wire around the probe tip. The resulting contact is unstable, introduces variable resistance, and risks damaging female pins rated for a limited number of insertions.
- Human error in documentation. Wrong serial numbers, skipped pin checks, misread schematics — all real occurrences. In one case, a set of cables was returned from a customer because the electrical diagram showed a connector without clear orientation markers. The technician wired the connectors backwards, and the person testing them misread the diagram the same way. The cables passed a test they should have failed.
- No standardized process. Whether a cable even gets a formal Acceptance Testing Procedure (ATP) is up to the project's technical lead. Some cables ship with minimal verification.
Timing a batch of ten 12-conductor cables, the manual test averaged 7 minutes and 28 seconds per cable — with one outlier hitting 9:34 due to a false alarm that required investigation. For a 59-conductor harness, the first manual test took three hours, with subsequent tests averaging two and a half. With 18 of those harnesses on order, that's roughly 45 hours of manual probing.
And then there's the extreme case: a VPC iCon connector with 320 pins. A full short-circuit check on a single pin means probing against all 319 others. Across every pin, that's nearly 100,000 probe points. Nobody is doing that by hand.
Setting the Requirements
Before evaluating specific products, I established a minimum set of requirements any tester would need to meet:
- Fault detection: Open circuits, short circuits, and miswired connections — the full manual test, automated.
- Documentation: The tester must generate a report with cable type, serial number, operator name, timestamp, and per-connection measurements. Ideally saved to a network folder, not just a USB stick.
- Adaptability: This is the critical one. Konrad Technologies doesn't produce thousands of the same cable. The connector mix changes project to project, often involving rare or proprietary customer connectors. The tester's interface must be reconfigurable without complex design work or outsourced adapter boards.
- Expandability: Test point count needs to scale for higher-conductor cables and harnesses.
- Minimal process disruption: The tester replaces the electrical verification step. Everything else — visual inspection, cable design, documentation workflow — should stay as close to the current process as possible.
- Low training overhead: Any operator should be able to run a test without specialized knowledge.
Evaluating Three Testers
Dynalab NX Pro
The NX Pro ships with 128 test points, expandable to 512. It detects all required fault types and stores results to USB. At $3,612 it checks the boxes on paper. The interface uses card edge connectors, which work but are somewhat difficult to customize designs around. The company offers modular options, but it's not the most flexible platform for a constantly changing connector set.
Cirris 4200
Also 128 test points at base, expandable to 1,024. Full fault detection, wireless network storage support. The problem is adaptability — the tester uses a proprietary connector board system split across four interfaces, each expecting a dedicated adapter board. The expansion modules are physically large, making it difficult to build a cohesive fixture around the system. For our use case, the Cirris 4200 didn't make the cut.
CableEye M3Z (CAMI Research)
The CableEye M3Z is a screenless unit that relies on a connected PC or NAS for test management and storage. It ships with the same 128 test points but expands to 2,560 — far beyond the others. Expansion modules stack vertically, keeping the footprint manageable. It detects all required faults and includes a built-in database management system for storing cable tests.
The interface is what sold it: a standard 64-pin AMPMODU connector from TE Connectivity. This means you can design PCB-mount fixtures, build dedicated test cables with the connector on them, or — for quick turnaround — just use pigtail cables terminated to ferrules and plug them into readily available terminal block boards. No proprietary adapter ecosystem, no outsourced boards. When a batch is done, pull the pigtails off the terminal blocks and store them for reuse.
Hands-On with the CableEye
To validate the evaluation beyond spec sheets, I requested a demo unit and ran it through a real-world test. I designed an 18-conductor cable with five DB9 connectors in Microsoft Visio — matching the existing design workflow — then built the cable and put the tester through its paces.
Designing the Test in Software
The CableEye software offers two methods for building a cable test: netlist entry and a graphical drag-and-drop interface.
The netlist approach maps directly to how ATPs are already structured at Konrad Technologies — a table of pin-to-pin connections. Since engineers already derive this information from electrical drawings, the transition is nearly seamless. This format also opens the door to automation: a macro in the cable design software could generate the netlist instantly, leaving only connector design for the user.
The graphical mode lets you drag connections between pins on-screen. It's intuitive for simple cables, though it can get visually cluttered on higher-conductor designs.
Connector design is the more time-intensive step. Connectors vary wildly between projects and are often proprietary. The CableEye software handles this by letting you upload a PNG image of the connector, then place pins directly on the image with a placement tool. The software numbers them automatically in the order placed. There are also built-in primitives for generating standard pin patterns without an image. Once a connector is designed, it's stored in a database and available for reuse by anyone with access — a significant time saver across projects.
Building the Test Fixture
For the pigtail approach, each conductor in the cable needs a test point on each end — so you're building two pigtail wires per conductor. Using the build shop's standard estimate of five minutes per wire, fixture assembly time scales linearly with conductor count. For a 12-conductor cable, that's about two hours of fixture build time. For a 59-conductor harness, it's longer, but it's a one-time cost.
The real efficiency gain comes from the tester's pin mapping feature. You don't need to connect pigtails to the terminal blocks in any particular order. The software displays the connector image, highlights a pin, and waits for you to probe it. The tester maps the probed pin to its terminal block position automatically. This means reassembly after storage is fast — no wiring diagram needed for the fixture itself.
Test Execution
Once the fixture is wired and mapped, testing a cable takes about 100 milliseconds for a 64-conductor count. The operator's job is reduced to: plug in the cable, press the test button, unplug. The tester automatically saves a detailed report — cable diagram, netlist with measured values, pass/fail status, notes, and documentation metadata — to the configured storage location. No hand-written ATRs, no scanning, no transcription errors.
The Time and Cost Math
For a 12-conductor cable, the automated approach requires more upfront time (fixture build) than a single manual test. The crossover point — where automation starts saving time — sits at around 15 cables for that conductor count. Below that, manual testing is faster in total.
For a 59-conductor harness, the math shifts dramatically. The crossover point drops to just two cables. With 18 harnesses on order, automated testing would save roughly 40 hours compared to manual testing — and that's a conservative estimate that doesn't account for the troubleshooting delays that inevitably crop up during manual probing.
Once the initial fixture and test are built, they stay in inventory. Duplicate orders of the same cable — or cables reusing the same connectors — benefit from that prior investment immediately.
The Quality Argument
While the time savings are compelling for higher-volume or higher-conductor cables, the primary case for the CableEye M3Z is quality improvement.
The tester eliminates DMM inconsistency, unstable probe contact, and human interpretation of schematics from the electrical verification step. It checks every pin against every other pin for shorts — including that 100,000-point check on a 320-pin connector that no one would do manually. The generated report is consistent, complete, and machine-produced. The backwards-connector incident that triggered a customer return simply cannot happen the same way when the tester is comparing the cable against a known-good netlist rather than relying on a technician's reading of an ambiguous diagram.
One Practical Limitation
There is a real constraint worth acknowledging. Many cables at Konrad Technologies terminate to fully custom proprietary connectors provided by the customer. In some cases, obtaining the mating connector is extremely difficult or impossible. Without a mating connector, there's no way to build a test fixture — regardless of how good the tester is. Fabricating a prototype connector in-house is theoretically possible but introduces its own quality risks from poor fabrication.
This means the cable tester won't cover every cable that comes through the shop. But for the cables it can cover, the quality and efficiency gains are substantial.
Recommended Process Integration
The suggested workflow with the CableEye M3Z integrated looks like this:
- Design the cable electrical diagram (unchanged from current process)
- Create the automated test setup — design connectors in software, enter the netlist
- (Optional) Design a test fixture — only necessary for cables exceeding 64 conductors
- Build the cable (unchanged)
- Build or assemble the testing interface — pigtail cables for simple jobs, dedicated fixtures for complex or high-volume work
- Test the cable — plug in, press test, done
- System integration (unchanged)
The cable design phase is unaffected. Developing a test is functionally equivalent to developing an ATP. The fixture assembly is the only net-new step, and for cables under 64 conductors using simple pigtails, it's straightforward. Previously built fixtures and automated tests remain in inventory for future use — meaning duplicate orders are essentially free to test.
Takeaways
An automated cable tester like the CableEye M3Z makes the most sense when the goal is consistent, reliable quality across a diverse set of cables — not just raw throughput. The time savings are real but conditional on volume and conductor count. The quality benefits apply to every cable tested, regardless of quantity.
For an engineering services company that builds custom test systems with constantly changing cable requirements, the CableEye M3Z's combination of a simple physical interface, flexible software, reusable connector database, and automatic documentation makes it the strongest fit among the options evaluated.
This article is based on a senior thesis project completed at Kettering University in partnership with Konrad Technologies. The evaluation was conducted using a CableEye demo unit on real production cable designs.