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Siemens 840c Alarm 1361 ORD2 Z contamination meas. system axis


Apr 11, 2020
(I posted this question to the siemens forum, but I don't know how much traffic it gets and wanted to see what anyone here might know about this)

I have an old Hyndai Hit15s cnc lathe with siemens 840c controller I have the following alarm: "1361 ORD2 Z contamination meas. system axis"

This problem has been occurring every day, but at times we can get it to go away by cycling power. There is a previous post with this same alarm that was caused by a stuck proximity switch. We generally will press the proximity switch by hand between cycling power to see if the alarm will clear with inconsistent results.

I have done the following on my machine to try and resolve this issue:

-Pulled and cleaned proximity switch.

-Verified function of switch. Switch receives 24v DC and is normally closed. When pressing the switch by hand the light on the associated DMP module turns off and back on when released.

-Checked 24v wire connections are tight. (Blue wires labeled DCV and P24 directly below it on the buss bar)

-Changed entire DMP board with one from another machine.

-Changed communication wire from DMP to PLC board (labeled X131(PLC)).

-Changed the PLC board.

None of the above has corrected the problem or seems to make any difference.

??? Would anyone be able to explain what the problem might be??? I don't even know what the alarm is suggesting might be the problem. I'm a machinist, not a technician, but often times get stuck with repairing problems when they arise. We have quite a few of these old machines, but this is the first time this particular problem has come up.

I'm not absolutely certain this applies, but the sinumerik 840c diagnostics guide has the following information:

136* Contamination measuring system axis POWER ON


Interlocking of NC START

Interlocking of Mode Group Ready

Machining stops

On measuring systems with a contamination signal (e.g. EXE) an error is sent to the NC from the measuring system. Check the measuring system in accordance with the manufacturer’s instructions.

Thank you all for any help you can provide!
Everything I can find about the alarm (which Isn't allot) points to the switch. You say you have more of these machines? How hard Is It to swap that switch with another machine and see If the problem follows the switch or remains on the same machine?
Thanks for the response. I haven't changed the switch yet because it appears to be working correctly, but that's a logical next step. I don't think it will be that hard to do. I'll report back once its done.
Sorry I don't have much to contribute to solving your problem. I just thought I'd mention that the Siemens forum is actually pretty good from my experience. The format seems outdated but I've gotten very helpful response to a few of my questions on there.
I think the switch is the wrong direction to look. I would bet this machine has "external pulse shaper electronics" (or EXE, in Siemens and Heidenhain speak). It looks like this alarm is triggered when the EXE says so, probably because the voltage from a sinusoidal output encoder or scale is too high or too low.