Read absolute encoder in cRIO 9076

[ExcelX]

Hi

I am trying to use cRIO 9076 and NI 9401 to read an absolute encoder (http://www.gpi-encoders.com/PDF/A58.pdf).  I am hoping that this is feasible.  Can someone please advise if there is any example or tutorial that explains how I can process the digitial input data to get a numeric position output?    Thanks.

[charris · Accepted solution]

Hello:

Are you using the A58-12 encoder? (That's the only one that looks like it will work with the 9401). If so, it returns data using the SSI serial protocol.

You'll need to configure a clock output and SSI data input line on the 9401. For reading the data, there is an FPGA SSI example on the community linked from this KnowledgeBase Article.

Hope that helps out!

[ExcelX]

Thank you.  Can you please advise why you think only A58-12 will work with NI 9401 while others will not?  Thanks again.

[charris]

The 9401 is limited to a total of 8 digital inputs. It appears that the other devices return each bit as a digital output, and they all appear to require more than 8 digital inputs. The A58-12 (because it uses SSI) is the only device in the manual that requires fewer than 8 digital inputs/outputs.

[ExcelX]

Accoridng pages pages 4 & 5 of the user manual, all four sensors (12,14,15,16) support the SSI output interface.  Can you please take a look and advise?  Thanks

[charris]

Ah, my fault; I missed that. Which model are you using, then? I think the external wiring connections will be the same, but the timing requirements may change slightly. The instructions above should still work.