Comprehensive Guide to Learning PLCs
Mastering the Fundamentals: Basic Bit Instructions in Studio 5000
The first step in programming any Allen-Bradley PLC using Studio 5000 Logix Designer (or RSLogix 5000) is understanding the core Bit Instructions. These simple instructions are the building blocks of all ladder logic and are critical for controlling inputs, outputs, and internal logic flags.
Key Takeaways for Beginners. Look vs. Write: Instructions that Look (XIC, XIO) are inputs to your logic. Instructions that Write (OTE) are the outputs that change the state of a tag.
XIC = Go Look for a 1. If it sees a 1 then it will be TRUE. If it sees a 0 then it will be FALSE.
XIO = Go Look for a 0. If it sees a 0 then it will be TRUE. If it sees a 1 then it will be FALSE.
OTE = If you can trace a continuous path of trues from the left side of the rung to the OTE then it will be TRUE, otherwise it will be false.
TRUE = Go write a 1
FALSE = Go write a 0