RsLogix 500 - Sequencing Machine Steps Part 5 - Word/Bit Manipulation

In this lesson you will dive deep into how the LAD 6 WORD routine of the previous RsLogix 500 - Sequencing Machine Steps uses integers and their associated bits to sequence through steps.

This method is used quite a bit in industry and is a great exercise in manipulating 16 bits by simply changing a single number. You see this on lots of machines that have optional steps. So most of the time a machine does steps A, B, C, D, and E but on a particular type of part D is omitted. By simply putting a 16 into B3:1 instead of an 8, you can skip that step.

The advantages of this method is that it can be universally used across practically any brand or model of PLC and a single instruction can manipulate 16 bits at a time.

1.  Download the CougarTurnSignalWord.RSS file.  This is a simplified version of the RSS file you used in the Sequencing Machine Steps lesson, only including the Word Sequence programming.

2.  Open the RSS file in RsLogix 500, download it to your PLC, switch the PLC to Run Mode, and Go Online.

3.  Open up the LAD 6 WORD routine.

4.  Turn on I:0/0.  It should still be wired to the Green button from the previous lesson.

5.  You screen should be sequencing through rungs 0-5 similarly to the video below.  You may have to right click the image below and open and new tab depending on your browser.



Below is the explanation of how the integer keeps track of which step in the sequence the PLC is on.  We are ignoring the XIC I:0/0 left turn signal in the explanation below for simplicity.

The key to understanding this method is understanding that the integer B3:1 is directly linked to the values of B3:1/0 through B3:1/15 since they are in fact the same number.  So B3:1 equaling 1 will always mean B3:1/0 is a 1 and B3:1/1-B3:1/15 are all 0.

After that, this one sequences exactly the same as the previous RsLogix 500 - Sequencing Machines with Cascading Timers and RsLogix 500 - Sequencing Machines with Counters sequencers.


Continue to the next lesson, RsLogix 500 - Sequencing Machines Part 6 - Multiplying Integers by Two.

Next Steps

Go to the Allen Bradley RsLogix 500 PLC Training PLC Training Getting Started Lesson series to select your next lesson.  There are also many other Lesson Series on PLC Programming and Industrial Automation.