Connecting SSI Instrumentation to a Compact RIO

[David-n-MO]

I know this is really late, but it may help someone else.  I have used the 9411 to receive the data and then I used a 9475 driving a montrona differential driver to drive the clocks to the encoders.  I use it to receive ssi position from seven motor encoders and it  has worked well.  If the clock  receiver on the encoder is optoisolated then the 9475 can drive the signal directly, but as in my case it had a differential receiver and NI had no true differential driver. i could have and should have just used two bits from the 9475 to drive the clock.

[KALee]

This is also very late, but I thought I would pass on what I did to make this work with a 9401 module only. 

My SSI board was the VEGA 2790504 Synchro Resolver to Absolute SSI Converter Board (http://www.vegacnc.com/html/vega2790504.htm)  The follwoing technique was suggested by the manufacturer of my board.  However, it mighit work for others.

For the Clock, I used two channels on the 9401, one for the Clock+ signal and one for the Clock- signal.  The channel routed to Clock- was always inverted from the channel routed to the Clock+.  Generating this inverted pair of channels was close enough to a real differential Clock output for my SSI board.

For the Data, I simply read the Data+ line coming back from my board on one 9401 channel. Ignoring the Data- didn't seem to make a difference.

So, each of my SSI devices consumed 3 channels on my 9401 (2 out, 1 in).  Since the 9401 can have 4 channels going out while 4 channels are coming in, I was able to connect 2 SSI devices to each 9401 module in my chassis. 

Hope this helps.

[Ben_Kohnen]

Dear all,

we finally got our SSI angular encoders and it is now time to implement those. I currently have the CRIO with NI9401, NI9411 and NI9871 at my disposal. The angular encoders are 18&12bit absolute encoders from SICK.

On that premise I wanted to ask what would be the best option here and if someone could share a short example of how they implemented it.

With best regards,

Ben

[NASmith]

Hi Ben, 

Hoefully the information in the below article will help you implement your solution. 

https://forums.ni.com/t5/LabVIEW/Encoder-Speed-and-Direction-Reading-with-NI-9411-and-cRIO-9073/td-p...

Kind Regards, 

Nathan 

[phenominafree]

hello,

I have to read data from serial encoder using crio ni 9022 and digital I/o ni 9401.

I downloaded the example LVFPEASSI, but when running, there were broken lines. I d'ont know how to fix errors. So could you send me your VI (perhaps it will help me).

Cordials salutations