Expectations and technical limits

This is necessary to be able to use measuring instruments sensibly.

A new high-quality measuring device …

… used to attract a lot of curiosity and respect. One hardly dared to turn one of the control knobs – it could have been easily damaged.

Today we have – through constant presence – a much more relaxed relationship to technical equipment. There’s an app for everything: download, run, done. If this does not work right away, changes can be easily revoked. Usually, there are no serious consequences to fear.

As a result of this process, the expectations of the technology have also changed. Devices must be robust, easy to use and understand without much knowledge.
If I don’t understand something right now, then I need another app that solves the problem for me. However, we do not want to deal with the background to a problem. Changing something manually or spending more than a few minutes dealing with a topic is no longer on the agenda.

That’s how you get carefree first,
later unsuspecting and finally reckless.

This is different in industry.

Here, basic knowledge and the desire for something new is still in demand and necessary – both for setting up new systems and for maintaining or repairing existing systems and plants.
Systematic networking has reached all areas of technology. But this also means that more and more people have to deal with the issue.

The consequences have a massive influence on entire occupational fields. A machine fitter can’t work any longer without a laptop. Meanwhile, he also needs special measuring instruments to check his machines and to find errors successfully. No 32 mm open-end wrench helps and with the multimeter alone you won’t get very far.

Unfortunately, the experience of networking from the private environment and the resulting expectations regarding networking in automation now stand in the way of our machine fitter. He thinks a special device can solve his problems in minutes. He expects a clear indication of the existing problem without having to think about it further.

Unfortunately, we have to disappoint our mechanic at this point.

Screenshot Youtube

Let’s take a little mental trip to the garage. There the mechanics now know from painful experience that an error message on the display of their OBD diagnostic device is just a snapshot of the past. “A “lambda probe fault” does not mean that replacing the probe will solve the problem – even if this is done in 90% of cases for profit’s sake. Many other causes can be considered, for example, a loose hose over which secondary air is sucked in.

To understand this, one has to deal with the function of the probe and the control of the motor. The OBD diagnostic device is more or less only able to read the error memory of the controller, not to investigate the cause.

Wrong expectations

Unfortunately, it happens that the users of our diagnostic devices also approach the matter with the wrong expectations. The new expensive device is hardly noticed and put aside. Once the day of the first use is here, a work instruction is expected directly on the display as to what to do to remedy the sporadic standstill of the machine.

Don’t misunderstand us, we would love to build such a device, but it will not come to that. The systems are far too different to be able to do such things. And also because the measuring devices can read much more than just error memory, extensive training is necessary if the device is to be used sensibly. Our technician or mechanic will not be able to do much with the measuring instrument unless he is willing to invest time for learning the basics, time for learning the possibilities and limitations of the measuring instruments and time for practical measurement and testing.

Our technician won’t be able to do much with the device.
if he’s not willing to invest time.

Basics: how does the CAN bus work, how are data exchanged, what interferes with communication, what does a good structure look like and which errors should be avoided.

Secondly, you have to deal with the measuring device itself. What can the meter actually measure? How do I operate the device? Which work steps do make sense? Which readings do I expect in a good bus or in a bad one? The issue of “What can’t I measure with it?” is also important.

Then it’s time to try out what you’ve learned: First on a working bus: does the meter show the expected data? What happens when I make small changes? How does the meter interpret this?

AI – artificial intelligence – is currently on everyone’s lips. But what does AI only do? It stores what is normal by feeding the system masses of data. Without a comparative value, it is hard to judge whether something is good or bad.

Therefore, after the first attempts to walk with the new measuring device is far from over. The task now is to create a database with reference values. You run the risk of classifying a signal as “good” too quickly just because you never saw it before and have no database as a reference. Therefore, technicians should measure at as many points in different operating modes as possible on their systems, collect as much data as they can, compile and store lists of nodes and documentation in a meaningful way – preferably before a first failure occurs. For example, it makes little sense to measure at a single measuring point in the vehicle even though the structure has four different bus segments. Here, at least one point should be measured at each segment, preferably at the beginning and end.

But even with all this preparation, finding a mistake will still not be trivial. It is now a matter of making meaningful measurements and drawing the right conclusions in comparison with the old measurement data. Is the bus disturbed at all? Is the bus itself a problem or is the problem somewhere else? Questions that are easier to answer by comparison than without data.

It always helps to base troubleshooting on a systematic, logical procedure. Unfortunately, there is no magic formula for this (see complexity and diversity of systems). But once you have gone through the above steps, you have the best prerequisites to solve the problem, find the fault and get your machine up and running again. A technician who has taken these steps has accumulated a wealth of experience that cannot be taken away from him. And with every use, the treasure grows.

Final question:
What does our technician know without a measuring device?

fieldbus knowledge

20. November 2018

Evaluate bus load

14. June 2018