SLC 500 Block Transfer

[mjkoc518]

With the data file of a BTW or BTR you can have a max of 64 words. Can anybody tell me why that is? With your logical rack and group set up your only have 32 words of Input and 32 Words of Output.

Now I know that equals 64 but when you use a BTW or BTR aren't you just using either an Input or Output? For example with a BTW you would being using your Output image to write data to your selected destination. Am I not understanding something?

Thanks

 

[Ken Moore]

Generally speaking, the two things you're trying to relate, are unrelated.

The 32 words of the scanner card, are usually used for discrete I/O.
While the BTW & BTR can be used for analog I/O or panelviews (Things that need more than 1 or 2 words). The Block transfer reads and writes are typically to and from an integer file in the SLC such as N7.


The Allen-Bradley knowledge base has some very good examples of Block transfers with the SLC's.

One gotcha, the CPU has to be series C or better to support Block transfers, otherwise you have to read and write directly to the M files of the scanner card, and it can be difficult to keep track of which memory location goes to what.