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Mapping to a Single Element in an Array
dmturner posted a topic in Allen Bradley / Rockwell AutomationI have 23 Micrologix 1400s and I want to take the same register, N100:99, out of each one and put in a single array in a CompactLogix L18ER. From what I have tried, it only seems like I can only map a range of integers, N100:77-N100:100, to the array and not an individual register to a particular element. (For example, mapping N100:99 from machine 16 to Selected_Model) Can you map to individual elements in an array? If so, are there any instructions on how to do so? Thank you in advance for reading my post!
How big is a sub-element ? (SLC/MicroLogix)
gazroo posted a topic in Allen Bradley / Rockwell AutomationHi there, As a software engineer, but a newbie to the Allen-Bradley world, sorry if this question doesn't make sense. I'm enhancing an existing driver by trying to add the ability to read/write structured and array data types - rather than just the elementary data types it supports right now. This following question is only in the context of SLC/500 & MicroLogix 1400. And I'm currently working on a Counter as a test case, but any solution obviously needs to take into account other structured (and array) data types. One of the requirements is that the user should be able to select a specific atomic item within a parent structure/array that they want to read/write. So, using the Counter as an example, they might want to define a field which holds just the value of the accumulator. I know that I can achieve this with a CIP command. I specify file type 87 for counter, file number as 5 (my test example happens to be the standard C5 data file of counters), and element is 0 (for the first counter in C5). Bit number is irrelevant so remains as zero. I ask CIP to return me 2 bytes of data (to hold just the accumulator word). Finally, I tell CIP that I want sub-element 2 (because the accumulator is Word 2 of the whole structure). Sure enough, the CIP response gives me exactly the 2-byte accumulator value I was expecting, nothing more, nothing less. Success. My question is this: I knew I had to specify the sub-element as 2; this happens to work for a Counter because of the way it is structured as 3 words. However, it implies that the value I specify for sub-element is ALWAYS measured in units of 16-bit words. Is this a universal truth (i.e. works for other structured types too ?), or does the size of a sub-element depend on other factors, such as the file type ? Thank you in anticipation.