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# How can I transform a rectangular type signal into a speed curve by LMS?

Pioneer

Hi,

I want to know how can I transform a  rectangular type signal into a speed curve by LMS?
In fact, in my work I 'd like to measure the rotational speed of of a spindle of a machine-tool.

In the electrical cabinet of the machine-tool, an output was created in order to obtain a top per revolution.

So, the final signal is a rectangular type signal.

Thank you a lot,
Best regards,
Essia

5 REPLIES

# Re: How can I transform a rectangular type signal into a speed curve by LMS?

Siemens Legend

Hi Essia,

In order to measure rotational speed, you’ll need to go to channel setup to turn on the tacho channel:

After you turn on the tacho channel, then you’ll go to Tracking Setup workbook to set the trigger level, if the signal is zero to five volt, you'll need to set the trigger level to 2.5V, how many Pulses per rev is the signal?  60 Pulese per revolution?

Once you setup the correct parameters, you’ll able to see the raw pulses in the display below and the unit will be rpm.

Good luck!

Hong

# Re: How can I transform a rectangular type signal into a speed curve by LMS?

Pioneer

Hi,
First thank you for the response,
I work with this acquisition system:

So I have juste 8 inputs.

This is the cable from electrical electrical cabinet of the machine-tool:

And then, it is connectet to the first input:

But the cable is connectet to input 1 and not to tacho1, I didn't realize it should be done.

And to answer your quastion, an output of the machine-tool was created in order to obtain a top per revolution so one pulse per revolution.

# Re: How can I transform a rectangular type signal into a speed curve by LMS?

Siemens Legend

You need to connect to T1, not the 8 channels module.  You need a 4 pin lemo to bnc cable.

Hong

# Re: How can I transform a rectangular type signal into a speed curve by LMS?

Pioneer

Yes I used the a 4 pin lemo to bnc cable and I found this signal:There is a lot of noise in the signal, I don't know if this is normal or not.
If it is normal, is there any tool to filter it during the tracking setup.
because, in this case, the rotational spindle speed is 1000 rpm, but by LMS I found 229426 rpm which is not true.

Thank you again

Asia

# Re: How can I transform a rectangular type signal into a speed curve by LMS?

Siemens Genius

Hi Asia -

I think you need to 'zoom out' in the tacho window display using the +/- buttons at the bottom; your screen shot is showing only 0.005sec. of data, and if your 1 pulse-per-rev signal is at 1000rpm, the pulse will only occur roughly every 0.06sec.  The tacho window should be displaying a 'square wave', or possibly a 'sawtooth' signal, similar to the attached, and you then want to set the cross-level somewhere in the middle of the min/max range.  For instance, if your square wave varies from roughly 0.0v to 2.0v, your trigger cross-level would normally be set to 1.0v.  In the attached picture, the sawtooth waveform is roughly centered around 0.0v, i.e. -1v to +1v, and the cross-level is set to 0.6v.

Good luck,

Jason