For the Allen-Bradley PLCs and the simulator used, the input and output image areas (in addition to other data) are held in “data files”
Each “data file” in PLC holds information such as
- Discrete input values
- Discrete output values
- Values associated with timers
- Values associated with counters
- Status information etc.
PLC data files
I/O memory mapping
I/O located on the controller (embedded I/O) is slot 0.
I/O added to the controller (expansion I/O) begins with slot 1.
Example PLC Addressing
Basic PLC instructions
Study the basic PLC instructions used in ladder logics.
Click on the below topics to read further.
• Examine If Closed (XIC)
• Examine If Open (XIO)
• Output Energize (OTE)
• Output Latch (OTL)
• Output Unlatch (OTU)
• One-shot Rising (OSR)