Bit shift is used to shift the state of a bit, say first bit to the left or right [Depend on BSL or BSR] where the shifting is based on a constant change in state. Say for example you have an inspection on station #1 of the indexer and the reject station is a couple of stations later say station #8. Shifting the stored bit states inside a word or a group of consecutive words to the reject station can be achieved using bit shifting. Upon shifting the states of bits in the whole word/s are shifted, giving you a transition of state from one station to another when the indexer turns.
File - It is a group of bits, in which you want to transfer the state of bits. You can use any bit file say, B3. So B3:0 is a word in file B3. where B3:0/0 is the first bit in the word B3:0, and B3:0/15 is the last bit in that word. Each such word contains 16 bits. If you need to shift more than 16 bits, it uses B3:0, B3:1, B3:2 and so on [16 bits + 16 bits + .......]But there is limit on the maximum size.
Control - It is a register file say R6 where the instruction is used to store its various states, example position of shift, unload bit state etc. Each R6 word, say R6:0 consists of 3 word length [you do not have to worry of this]
Bit Address - This is the source of you shift instruction. If this address is ON/True when the instruction goes true, it shifts a 'state - one' to the first bit address of the file, or shifts a 'zero' when the state of Bit Address is OFF/False
Length - I think you should have guessed what is length by now. It is the count of number of bits you want to shift. Say your file address is B3;0. If you specify 16 or less the instruction use of word in the file. That is B3:0 itself, or if you specify anything between 16 and 32 it uses two words B3:0 and B3:1.
I do not have RS Logix at home, maybe tomorrow I can post an example. If this is not clear enough, ask, but be more specific.
Best Regards
____________
