How do I get rid of excessive null ('00') words when reading A-B Flex I/O using DeviceNet?

[Alan_Bentz]

I'm using NI's DeviceNet hardware and driver software and LabVIEW. On the I/O end I have Allen-Bradley's ADN module connected to Flex I/O. I can configure the module to do what I want, and although the information I need is contained in the data stream reply after the 'Read' request, I only need the first 22 words or so. I'm a Read reply of 256 words. Rockwell has not offered a solution.

[Chad_Pelletier]

This seems to be more of an issue from the Rockwell side of things. The only suggestion I have is to go ahead and receive the entire data stream into an array in LabVIEW, index out what you need and discard what you don't. It seems to me that there should be a way to shorten the frame size (either on the hardware or through RSNetworx/RSLinx)if only the first 22 words are being used. It is also my understanding that 22 words is the maximum number of words that the Flex I/O requires.

Chad Pelletier
Applications Engineer
National Instruments