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loop back test using PXI 6562 HSDIO card

hi.....

am performing Loop back test using PXI- 6562 card. I have SMA-2164 connector block for connecting the two channels.

 

I am generating LVDS signal on channel '0' using MAX & I am able to see the generated signal on CRO. but when I am connecting channel '0' to channel '8' (for acquisition using MAX) I am not able to get anything.

 

 I am using SMA male to SMA male but sometime when I use simple multi stand wire then I am able to acquire the signal. For connecting channels on SMA-2164 connector block, does we require any specific type of cables?

 

I think I have problem some where in cable. Any suggestion is most welcome.

 

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Hello,

 

I hope you were able to resolve this issue, but I thought I'd complete this thread with my thoughts on the current issue you are experiencing.

 

To generate a signal on channel 0 and read that signal on channel 8 using MAX, you will need to generate a constant '1' on channel 0, then switch over to channel 8 acquisition and see if you still receive a '1'.  If you want to generate a pattern, you will need more than MAX to accomplish this.  You can use LabVIEW, CVI, SignalExpress, or any other ADE of your choosing.  From there, you can set up a generation task on ch 0 to generate a pattern and read back that pattern using an acquisition task on ch 8.

 

Another thing to note is when you generate on ch 0, you generate between 0 and 1.  If you generate on other channels, you will need to be aware that each bit in the data byte you are writing corresponds to a channel.  Writing a '1' to channel 1 requires sending 0000 0010, which is equivalent to '2'.  So a toggle pattern on channel 1 is 0, 2, 0, 2 in your data array.

 

SMA to SMA should work just fine, there should be no issues with that.  I don't know why using a multi strand wire works better, it may be the cable itself.

 

Hope this helps.

Kyle A.
National Instruments
Senior Applications Engineer
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Thanks kyle for the reply

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Even now I am not able to do the loop back test. Now I am using Huber suhner 50 ohm cable for connecting two channels. I also try to do loop back test after giving High on the channel. 

 

Is it possible to do loop back test on PXI 6562.

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Hi R.V.,

 

It is possible.  I would recommend posting the steps/sample code you are using to perform this test, as it is difficult to tell why you are not able to perform a loopback. What are you sending (you says giving high so I assume a '1' on ch 0)? What are you receiving? What do you expect that isn't happening? Are you using internal clock or static timing(assume static)? How are you triggering(assume none)? 

 

50 ohm cables are what you should be using. No issues there.

 

I would also recommend trying two different channels to see if there is potentially a bad connection on just one channel.  Also, are you connecting ch0+ to ch8+ and ch0- to ch8-? I know its basic, but always good to double check. The silkscreen on the board is labelled as such.

 

Do you have a DMM to use as well? it may be good to probe the SMA connectors with an external DMM to verify the signals are being sent out from the 6562 correctly.  Should see 1.4V on one line, 1.0V on the other.  Anything different could indicate an issue with the system.

Kyle A.
National Instruments
Senior Applications Engineer
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Thank you kyle

 

Now I am able to do the loop back test. I did it using Labview example. 

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Hi Kyle

 

Now I am using PXI-6562 card for Reading writing Flash Memory. I am able to write the data into memory & also able to erase it. But I am facing problem in reading it. 

For reading the data from memory, first  I have to send a  Flash Read command to DUT in response of Reading command DUT will send complete data of Flash memory in LVDS signal form & I have to read that signal using PXI-6562 card & then decode it to retrieve the data. DUT Use Serial Asynchronous protocol (UART) at 1Mbps to transmit the Signal (Frame format=1 Start bit, 8 Data bit, 1Stop Bit) & Start, Stop bit are high signal.

 

Problem is that when I  Reset the card through MAX then by default all channel go into High State & then If I try to read memory data, I am to get the response on Digital waveform Graph. But I am not able to decode it as channel data remains high so I am not able to detect the start bit & stop bit.

 

If I change the state of that channel low from MAX & then If I try to read the memory data from DUT, I am not able to get the response on Digital waveform graph. Channel remain constantly in Low state.

 

I am attaching a VI (Flash Read data.vi), on the block diagram of this VI I pase snap shot of response on digital waveform graph & its corresponding data adjacent to it in 2-D Numeric Array.

 

Is there any way by which I can make Default state Low of all channels & after it I am able to read it??

 

 

 

 

 

 

 

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Hi Kyle,

 

am performing Loop back test between2 channels of same SMU 4143 card, am not able achieve this can you please help me out to solve this issue.

 

Attached the code for your reference (LV 2013).

 

Thanks,

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Hello,

 

This is an SMU issue, while this post is speaking to the 6562 Digital I/O instrument. I would encourage you to create a new post in the proper forum here: http://forums.ni.com/t5/Digital-Multimeters-DMMs-and/bd-p/80 and someone will help you with your question. Thank you.

Kyle A.
National Instruments
Senior Applications Engineer
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