Z axis contouring..... what is it?

If I move the turret on my Hyundai Lathe, Siemens 840C control, to the Z + limit I get the error " Z-axis contouring" I am then screwed and cannot do anything (z axis will not move) until I power down the machie and reboot it.

As with just about every error I have recieved now, this one is also not in the book.

Any help here?

Will try to post one question a day ACCUALLY metal working related to make this group meaningful again. Evenif they are beginners questions. I am catching on to this CNC stuff but I sure as hell ain't no expert.

Thank You, Randy

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I have nothing to add for your question because I've never worked with a Siemens control. But I'm glad to see someone trying to revive this group. I'll do my best to help the rebirth also ;)

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Unfortunately, this is pretty typical and is by no means only to certain controller or machine tool builders.

The guy that wrote the alarm tables isn't the same guy that programmed the plc--in fact, they might very well reside in different countries and don't even speak the same languages.

Consider yourself lucky that an alarm code actually gets tossed in the first place--much better than having the machine hang indefinately instead...

The best way to deal with this is to study the ladder and map each and every sensor, switch etc so that you can go to your diagnostic screen and verify whenever a machine-side problem occurs.

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The error message itself may be poor translation into english (from Korean?). Often CNC's will have a soft limit and a hard limit for each axis. The soft limit is supposed to keep it from ever hitting the hard limit. If it hits the hard limit then there is something wrong and it throws an error. The problem may be that the limit is out of adjustment or chips/crud is causing it to hit the limit early.


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maybe just stay away from that limit so you can finish your job

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Fanuc has a parameter for that--when properly set the jogged axis stops just short of the actual limit switch so long as you've performed an initial refrence return upon power up.

I would be quite surprised if it turns out the Siemens 840C is lacking a similar soft limit capability

--more likely you'll probably find that it was never activated or a default such as 99999999 was used.

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I'll need to do some looking at parameters I guess. There is only one dog hitting one switch.

Thank You, Randy

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I almost didn't recognize a CNC post with all noise...

Did the alarm have a number? Could there be more than one alarm active? On the 840D you can set the alarms to scroll through all active alarms. Not sure if the C can do that. There should be an alarm screen that shows all active alarms.

The contour error should be a Siemens alarm, not an OEM alarm. It normally means that the following error is more than expected. There are many parameter that can lead to this, but in a running system, it's more likely there's a mechanical problem. Could be a loose motor coupling, loose scale reader head, or even chips packed up near the end of travel.

Normally a contour error alarm is reset with the Reset key, and doesn't require a reboot. That's why I wonder if there are other alarms active.

Siemens has a pretty good web site with full documentation that you can browse on line or download a copy, at:

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116* Contour monitoring Reset key In all modes

When decelerating

When accelerating

At velocities greater than in NC machine data ?Contour threshold speed?

Interlocking of NC START

Interlocking of Mode Group Ready

Setpoint 0

The control enable is removed after the time stored in NC machine data ?Control enable cutout delay? has elapsed

Follow-up operation

At a velocity greater than in NC machine data ?Contour threshold speed?, the NC machine data ?Tolerance band contour monitoring? was exceeded

When accelerating or decelerating the axis has not reached the new speed within the time defined by the KV factor

Increase NC machine data ?Tolerance band contour monitoring?

Check KV (servo gain) factor

Check the optimization of the speed controller

Check the actual values (pulse encoder)

Check the free movement of the axes

Reduce acceleration

HTH, SteveA

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