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635 help for LabView Visa comm

BarryGalvin

New member
Hello,

I have been trying to comm with a 635LCD thru Labview Visa with very limited results. I am using the virtual comm port which has been validated at 115Kbaud.
I have tried the WinTest and watched the packets but can not enter them as text in the same way in LabView. Can anyone tell me a literal text or hex command to send to it such as ClearDisplay? If I can see how it is done I am sure I can figure out the rest.:(

Thanks,
Barry GRAE LLC
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I'm not familiar with Labview VISA, but I took a quick look at the Google hits. It seems like you would need a library or driver that knows how to handle the packet protocol for the 635, including calculating the CRC for each command. I have no idea whether such a driver is available.

For "canned" commands, you could get by with a static block of bytes that has the CRC included, but for "dynamic" commands where the data is variable, the CRC would have to be calculated on the fly.
 

BarryGalvin

New member
I can do a CRC-16 on the fly but the VI I found that does it does not agree with what I see WInTEst putting out. That's why I need to see one "literal" hex command so that I can deconstruct it. There is CRC-16 and CRC-CTTT and another question of how much to put thru the CRC at one time. The entire string is what the manual says but when I do that I get a different CRC than WinTest.

Thanks, Barry
 
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