Alarm in Bridgeport VMC 800 with Heidenhain TNC 370 CNC Control

Hi friends!

The subject machine displays the following alarm immediately after boot up...

"Z-Measuring system defective A"

The specs of the machine Z-axis are as under:

Z-axis drive: Siemens 6SN1118-0AA11-0AA0.
Z-axis motor: Siemens 1FTS074-0AC71-1-Z.
Z-axis encoder: ROD 350 500 P/R.

Any help regarding the problem will be highly appreciated. Also we need the parameters list with description of TNC 370 control. Is there any way to get the z-axis referenced without encoder? if yes how to proceed?

Waiting for any helpful response.

Rana Ali.

A = Signal amplitude error
B = Signal frequency error
C = Error with distance-coded scale

Possible error causes:
- Encoder not connected
- Cable damaged
- Glass scale contaminated or damaged
- Scanning head defective
- Encoder monitoring system defective

No axis can be used without the encoder.

Hi sir
1. How I identify encoder wire and signal A,B,C
Can we measured by scope or meter at which connecter pin no .any description of connecter or wire colours
2. What do you mean by encoder monitoring system defective which area(Hiedenhain Controller x3 connecter area )
Please guide
With best regard
Rana Ali

Z-Measuring system defective A = Signal amplitude error on Z-axis
Z-Measuring system defective B = Signal frequency error on Z-axis
Z-Measuring system defective C = Error with distance-coded scale on Z-axis

Amplitude error causes:
- Encoder not connected
- Cable damaged
- Glass scale contaminated or damaged
- Scanning head defective
- Encoder monitoring system defective

1: l1– (Yellow)
2: 0 V (White)
3: l2– (Red)
4: internal shield (White/Brown)
5: l0– (Pink)
6: l1+ (Green)
7: +5 V (Brown)
8: l2+ (Blue)
9: l0+ (Gray)

Hi It
Thanks for your help full response
Please guide me that its encoder round connecter wire colours or x1,x2,------ at hiedenhaon controller side 9 pins female d sube connecter

https://product.heidenhain.de/JPBC/i...78_00_a_02.pdf

https://product.heidenhain.de/JPBC/i...60_00_a_02.pdf

Thanks again
1) I change the machine parameter maesurong system monitoring all 000 or only z,
than z axis proper move to reference but can't complete reference position. After that I push emergency after resetting alram z axis move other direction not in reference position side.
And overtraval.I set again parameter.
2)
Dear sir I checked all connection found ok. Here I tell you that according to these manual I switch y to z connecters and also parameters .
One time massage shift, after one time another alram display and measuring monitoring alram removed.
( Grass positioning error show z D)
z axies suddenly drop when machine emergency stop release. And this alram display.
How I can removed this alram
Plz guide us
Rana Ali

Replace encoder!

Successor: ERN451 500, product ID: 376857-51

I will try