adccommunitymod (AutomationDirect) asked a question.
Simple one; What defines a "word"?
Created Date: May 15,2013
Created By: Dean
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As in the Directsoft5 free software being limited to 100 words. My guess is: A single contact or coil equals one word? Data as in a CLICK DS address equals one word? Data as in a CLICK DD address equals two words? How about advanced instructions such as compare, math, or drum sequences?
Created Date: May 15,2013
Created by: bcarlton
In the processor a 'word ' is the chunk of RAM memory which can be accessed in one clock cycle.
As far as instructions they would be defined interms of the number of those 'chunks ' the actual instruction and its arguments take up.
The CPUs you mention have 16 bit 'words '. The CPUs in the Allen Bradley ControlLogix line have 32 bit 'words '.
Created Date: May 15,2013
Created by: franji1
The PLC opcode words in a DL PLC are 3 bytes long. They typically represent an opcode in the HIBYTE followed by 2 bytes of of "paramter " information. Hence, there is (at least) 1 word per parameter. So, most contacts/coils use 1 word, although some of the more advanced paramters (e.g. bit of word or double constant) take up 2 words.
Ladder memory "words " must not be confused with data (V memory) words, which are 16 bits wide.
Created Date: May 15,2013
Created by: Dean
Thanks folks, that helps my understanding of the concept.
Created Date: May 15,2013
Created by: Dean
As in the Directsoft5 free software being limited to 100 words. My guess is:
A single contact or coil equals one word?
Data as in a CLICK DS address equals one word?
Data as in a CLICK DD address equals two words?
How about advanced instructions such as compare, math, or drum sequences?