IEC 61131-3 Memory Offset Mapper
Lay out PLC variable offsets with vendor-specific alignment rules and export tag data.
AEO summary
A PLC memory mapper lays out variable offsets according to vendor-specific alignment rules so you can build a cleaner tag map.
Use this page when you need a fast answer for where PLC variables are likely to land in memory across Siemens, Rockwell, Mitsubishi, and other common alignment styles. It helps you move from a list of tags to a structured offset table faster.
- Useful for PLC memory planning, HMI tag preparation, and documentation.
- Shows address offsets and size consumed for each variable.
- Helps reveal padding and alignment effects before implementation.
Architecture & Controls
Generated Memory Map
Memory map is empty. Add variables from the control panel.
How to read the result: each row shows the variable name, data type, calculated address offset, and the amount of memory consumed after the selected vendor alignment rules are applied.
Use the generated map as a planning and documentation aid, then verify final addresses against the real PLC compiler, data block format, and project conventions.
⚠️ Engineering Caution:
This tool is intended for screening and pre-check workflows. Results are usually directionally useful, but they
can still shift with equipment selection, environmental conditions, naming conventions, revision status, or
interpretation rules. Confirm any value that affects ordering, substitution, compliance, or installation before
acting on it.
IEC 61131-3 Memory Architecture
The IEC 61131-3 standard defines the programming languages and data models for programmable logic controllers. Memory mapping involves calculating exact byte offsets for variables in contiguous data blocks, respecting alignment rules specific to each PLC manufacturer.
Manufacturer-Specific Architectures
Different PLC manufacturers implement distinct memory alignment rules: Siemens uses 2-byte alignment for S7-1500, Rockwell uses 4-byte alignment, Mitsubishi uses 16-bit D-Register mapping, and the IEC standard defines its own generic alignment scheme.
Related Tools
AWG Calculator
electricalLook up American Wire Gauge diameter, cross-sectional area, resistance, and standard NEC ampacity values.
Motor FLA Calculator
electricalEstimate motor full-load current from freely entered voltage and power, with NEC table references for comparison.