pattern match

[Timothy 123]

Hi,

I have a pxi 6561. When I use pattern match, it can be on one of the aquisition and generation channels, and does not have to be on one of the trigger channels right.

Thank you

[garretth]

Hi Timothy,

You're correct. The pattern match can occur on any of the DIO lines (as long as they are configured for an acquisition session). The hardware recognizes the pattern and fires a trigger.

[Timothy 123]

The pattern match is used to match a series of patterns that occurs across the dio channels for one particular sample, correct. I am still fairly new to the nihsdio, but is there a way for me to use pattern match to match a pattern for one channel across many samples. Suppose I am interested in a waveform coming out of an ic that appears only after the pattern 11101 is aquired on one acquisition channel. Can I setup pattern match somehow to aquire after it sees this pattern.

[garretth]

Hey Timothy,

That's a really good question. I know that Pattern Match will not be able to accomplish this type of behavior. However, I think there might be another way. Scripting might be one possibility. I will check into this on Monday and get back to you when I find something out.

[garretth]

Timothy,

Ok. Unfortunately, the onboard hardware does not currently have any good way of "pattern matching" serial data on the fly. This has, however, been a requested feature and we can hope that it will one day be available. In the meantime, I can see two options:

1. Do the matching in software. You can look for a pattern in software and programmatically decide what to do once it's recognized.

2. Use a deserializer to convert the serial data into parallel data and then pattern match across several lines. The obvious drawback would be that you would require multiple digital lines to read one stream of data.

I know this probably wasn't quite what you were hoping for! I would definetely recommend making a product suggestion as our developers take these very seriously.

[Timothy 123]

Hi,

Do you know why the data position delay cannot be set to be any value between 25 MHz and 50 MHz. Is there a reason for this. Ihad asked this qeustion before and found out about the delay but do not know where it comes from. The previous thread is at

http://forums.ni.com/ni/board/message?board.id=270&message.id=3108#M3108

Thank you

[garretth]

I looked into this and found that it's simply a hardware limitation.

[Timothy 123]

Hi,

Are all the hardware limitations for the pxi-6561 documented somewhere. It would be great if you had some documentation of all the hardware limitations so I could plan ahead when building a large system. I have noticed 3 limitations so far

1. The "holes" in what the data delay can be set to
2. Waveforms must come out as multiples of 4
3. Waveform subsets must be > or = to 8. I tried to send out a waveform subset of 4, and it said it was to small.

Thank you,

-Tim

[garretth]

Message Edited by Garrett H on 10-27-2006 12:35 PM

[garretth]

Sorry about the above response.. I accidentally responded to a different question in this thread.

Tim, that is good feedback for us. These three limitations are noted in the NI Digital Waveform Generator/Analyzer Help document. This document outlines the operation and features of the HSDIO cards and also gives some good background info on these digital devices.