TechRedd86

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About TechRedd86

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  • Birthday 04/25/56

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  • Location Cleveland, OH

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  1. FIFO, SHIFT, ROTATE BITS

    I’ve used the FIFO and BSL/R functions in the AB PLC and SLC plc’s to track the number of parts or presence of part on conveyor systems for coating and curing of parts. I’ve saved time in coding and memory allocation. When writing code prior to final design or in copy and paste this is a proven method. When putting a batch of parts together or collecting data the FIFO provides load and data position signals. The chances of someone over writing your data are reduced. I’ve used in taking averages for process control in SLC’s. The load and unload functions work for the rotate of tools or parts thru a process. The unload bit goes to the load bit. With tying the unload and load steps in the same rung the FIFO length is held constant. This is essential in drying oven. Moving the data in one direction is part on the functions operation. Moving the data in the opposite direction takes a little planning. The FIFO needs to have open address in the start and finish positions required. The number depending on the reverse shift required. The triggers for load remain same with an added move statement to push the data in the required position in the stack. The only difference in the unload, instead of monitoring the unload word the unload position is checked. The data reverse is handled with a scan function, a move statement and some indirect addressing, to move the data down one position in the stack. The FIFO operation needs to be locked out during this step. Functions are our friends.