linear encoder with SCB-68

[Asabti]

I'm having a really difficult time trying to figure out how to connect  an RSF Elektronik Linear Encoder (type: MS 6x) to my SCB-68 and getting some sort of output from it, Can you guide me in some sort of direction please. Thank you

[Jochen]

Asabti,

the SCB-68 is just a universal connector block that fits to a huge number of different data acquisition boards. Which board are you using? Could please provide a datasheet for your linear encoder?

Thanks,

Jochen

[Asabti]

The DAQ card that I have is a PCI-MIO-16e-1 The linear encoder that i'm attempting to use it a RSF Elektronik MS 6x i can't find the data sheet for the exact model but i've attached a pdf which talks about the variouis signals that it outputs. Also the table below is a table that I found in the documentation for the MS 6x that I have which explains the various pin outputs of the encoder. I hope this help please let me know if you need any further information.

Thank you in advance.

Pin                   Signal

1                      +5 V                                                                Supply

2                      V Gnd              Analog ground              Output 2,5 V typical

3                      R1                    Analog voltage signal

4                      A2                   Analog voltage signal                2 Vss typical

5                      A1                   Analog voltage signal                2 Vss typical

6                      0V

[Asabti]

Also, I managed to get 3 diffrence voltage sine waves from the encoder the problem now becomes how do I go about coverting these three waves into a position graph in LABview.

[Jochen]

Asabti,

your DAQ board doesn't seem to be a good fit for your purpose. For precise measurements you need  the exact phase information of your signals, but as you do have a multiplexed board and not a simultaneously sampling board, this can't be achieved. Still if you are ok with a phase shift of 1 µs, you can acquire the signals with analog channels and do the calculations in software. Here you can find some more information and a different approach, that requires some additional hardware. Doing everything in software could become quite tedious and CPU consuming, so I don't really recommend that.

Another option is to use an external circuitry, that converts the sine waves in a quadrature encoder signal. These converters are commercially available from various vendors. Unfortunately the 16E-1 doesn't support X4 encoding, so without any additional circuitry you could use only 1/4 of the maximum resolution delivered by the converter box. Here is some more information about this topic. By the way, any board of the M-Series family provides direct connectivity to quadrature encoder signals with X4 encoding.

I hope this helps,

Jochen

[Asabti]

Thanks for the reply. I do have a PCI-6602 which is a general timer/counter card I belive.  If i understand correctly it would not be easy but it would be possible to get a position out of this linear encoder by using the present DAQ card and the time/counter card. Is this correct?

[Jochen]

The PCI-6602 supports direct connectivity for quadrature encoder signals. With an external converter box for your resolver-type signals, the 6602 would be a good fit for your application.

Jochen

[Asabti]

Jochen,

Are you implying that I need to convert my three sine waves (analog waves) into quadrature encoder signals using some sort of external box. If so, what kind of NI equipment is there or is this possible through the creation of external circuitry. Also, my output from the 6602 is 4 BNC plugs is this what you are referring to as direct connectivity.

Thanks in advance and sorry if all these questions seem elementary

[Jochen]

Asabti,

your device seems to be a resolver with sine/cosine signal generation (A1, A2). The third sine wave is probably a reference signal, that provides an absolute reference within one revolution. As already stated, there is no good direct way to measure these signals with your current hardware. In one of my recent posts, I have referred to the SCXI-1540, which could be an option for you, but this would require a complete SCXI-system, which might be a bit of an overkill for your application.

There are multiple vendors, that provide external converter boxes for resolver signals to quadrature encoder signals. Heidenhain is one of them, but it might be also a good idea to check with the vendor of your encoder.

When I was talking about "direct connectivity to quadrature encoder signals", I was not referring to any BNC or other type of connectors, but to the fact, that the PCI-6602 accepts quadrature encoder signals without any external circuitry. Please refer to the manual of the PCI-6602 for further instructions.

I hope that helps,

Jochen

[acanivell]

Hello

The SCB-68 has got a bread board area, where you can place a Schmitd Trigger circuit that can convert the sine into a TTL compliant pulse.

But if you want, there are 3rd party PXI manufacturers like Pickering, who sell bread-board modules that you can insert into the PXI chassis

I hope this helps, late maybe according to the last date of the thread, but nice any way.

Cheers