S5 Absolute Addressing vs. S7 Symbolic Addressing
Why S5 uses absolute addresses (E 0.0, MW 10, DB10.DW5) and S7 prefers symbolic names (Start_Button, Temperature, Motor.Speed). Migration strategy for converting absolute to symbolic.
S5S7addressing
PLC Knowledge Base
Guides, references, and practical tips for PLC engineers
Essential Guides
Essential Guides
PLC Memory Optimization: Reducing Data Block Usage
Practical techniques for reducing PLC memory usage on S7-300/400 where memory is limited. Covers DB optimization, marker cleanup, dead code removal, and string handling.
8 min read
Essential GuidesMitsubishi A-Series to iQ-R Migration Guide
Overview of migrating Mitsubishi MELSEC A-series PLCs to the iQ-R platform. Covers software conversion (GX Works2/3), hardware changes, network migration (MELSECNET to CC-Link IE), and common pitfalls.
8 min read
Essential GuidesSchneider Modicon to M580: Migration Overview
Overview of migrating Schneider Electric Modicon Quantum and Premium PLCs to the M580 ePAC. Covers the Unity M580 Application Converter (UMAC), hardware mapping, and EcoFit modernization services.
8 min read
Essential GuidesCross-Platform PLC Migration: Siemens to Allen-Bradley
What to expect when migrating between Siemens S7 and Allen-Bradley ControlLogix. No automatic conversion exists — this guide covers the manual approach, key differences, and planning.
8 min read
Siemens S5 → S7 Migration(10)
Step-by-step guides for migrating S5 programs to S7, including AWL conversion, address mapping, and timer handling.
Pillar Guide
Handling S5 Special Function Blocks (OB, SB) in S7
How to migrate S5 organization blocks (OB) and step blocks (SB) to S7. Covers OB number mapping, startup OBs, interrupt OBs, and SB conversion strategies.
·12 min readS5S7OB
8 min read
Migrating S5 Counter Programs (Z/ZV/ZR) to S7
How to migrate S5 counter programs to S7. Covers ZV (count up), ZR (count down), BCD format differences, S7 equivalents (S_CU, S_CD, CTU, CTD, CTUD), and common pitfalls.
S5S7counter
Understanding S5 Data Blocks (DB0, DB1, DX0) in S7
What are S5 system data blocks DB0, DB1, and DX0? Why they exist, what they contain, and how to handle them during S5 to S7 migration.
S5S7data block
S5 Function Blocks to S7: FB/FX Migration Guide
How to migrate S5 function blocks (FB, FX) to S7. Covers parameter passing differences, formal operands vs. block interface, instance data blocks, and standard FBs (FB250, FB251).
S5S7function block
The Siemens S5/S7 Converter Tool: What It Does and What It Doesn't
Honest assessment of the Siemens STEP 7 S5→S7 conversion tool. What it converts automatically, what it cannot handle, common errors, and how to deal with the remaining 20–40% that requires manual work.
S5S7converter
S7-300/400 → S7-1500(5)
Modernize legacy S7-300 and S7-400 systems to S7-1500 with TIA Portal.
Pillar Guide
Optimized vs. Standard Data Blocks in S7-1500: What Every Migrator Must Know
Complete guide to optimized vs. standard (non-optimized) data blocks in S7-1500 and S7-1200. Architecture, performance, migration impact, PUT/GET compatibility, OPC UA, and when to use which.
·12 min readS7-1500data blocksoptimized
STEP 7 Classic to TIA Portal: What Changes for the Programmer
A practical guide for experienced STEP 7 Classic programmers moving to TIA Portal. Covers the 15 most important differences in daily workflow: editor, tags, DBs, compilation, online access, debugging, and gotchas.
STEP 7TIA PortalSIMATIC Manager
S7-300 End-of-Life 2033: Migration Timeline & Planning
Practical migration timeline for S7-300 plant operators. Year-by-year plan from 2025 to 2035, covering spare parts availability, price escalation, and prioritization of critical systems.
SiemensS7-300S7-1500
S7-300 to S7-1500 Migration: Complete Guide
Step-by-step guide for migrating Siemens S7-300 PLC programs to S7-1500 using TIA Portal. Covers hardware mapping, software migration wizard, optimized data blocks, AWL→SCL conversion, and common pitfalls.
SiemensS7-300S7-1500
STL/AWL Deprecation in S7-1500: Why You Must Convert to SCL
Why AWL/STL runs only in emulation mode on S7-1500, what that means for performance and maintainability, and how to convert your STL code to SCL. Includes conversion strategy and code examples.
AWLSTLSCL
AWL / STL Reference(3)
Instruction set overview, command syntax, and S7 equivalents for Siemens AWL/STL.
Pillar Guide
Optimizing PLC Scan Time: Practical Techniques
Practical techniques for reducing PLC cycle time. Covers code structure, conditional execution, data type selection, optimized data blocks, and interrupt-based architecture.
·10 min readPLCscan timecycle time
Understanding Legacy PLC Code: Pattern Recognition Guide
How to read and understand undocumented legacy PLC code by recognizing common patterns: self-holding circuits, step sequences, safety interlocks, analog scaling, and communication blocks.
PLClegacy codepattern recognition
Reading and Understanding S5 AWL Code: A Practical Guide
Learn to read Siemens S5 AWL (Instruction List) code from scratch. Covers the accumulator model, bit logic, load/transfer, timers, counters, jumps, and data blocks with real code examples and line-by-line explanations.
S5AWLSTL
SCL / Structured Text(2)
Syntax reference, tutorials, and best practices for Structured Control Language.
Pillar Guide
Converting Ladder Logic to Structured Text: Why and How
When and how to convert PLC ladder logic (LD/KOP/LAD) to Structured Text (ST/SCL). Covers the benefits, conversion patterns, what to keep in ladder, and practical examples.
·8 min readLadder LogicStructured Textconversion
Refactoring Legacy PLC Code: From Spaghetti to Structure
How to refactor messy legacy PLC code into maintainable structure. Covers identifying spaghetti code, step-by-step refactoring, when to refactor vs. rewrite, and practical examples.
PLCrefactoringlegacy code
Understanding & Documenting PLC Code(2)
Practical guides for reading, analyzing, and documenting undocumented PLC programs.
Pillar Guide
Taking Over an Undocumented PLC System: A Survival Guide
Practical step-by-step guide for technicians taking over an unknown PLC system. Covers the first-week checklist: hardware audit, program backup, risk assessment, spare parts, and building system knowledge from scratch.
·14 min readPLCundocumentedmaintenance
How to Document a PLC Program Without Original Documentation
Practical step-by-step method for documenting an undocumented PLC program. Covers block inventory, I/O tracing, cross-reference analysis, symbol table creation, and generating useful documentation from raw code.
PLCdocumentationundocumented
Allen-Bradley Migration(7)
Guides for migrating and integrating Allen-Bradley / Rockwell PLC systems.
Pillar Guide
Cross-Platform PLC Migration: Siemens to Allen-Bradley
What to expect when migrating between Siemens S7 and Allen-Bradley ControlLogix. No automatic conversion exists — this guide covers the manual approach, key differences, and planning.
·8 min readcross-platformSiemensAllen-Bradley
IEC 61131-3 Compliance: Making Your PLC Code Portable
How to write PLC code that is portable between different manufacturers. Covers IEC 61131-3 compliance levels, vendor-specific extensions to avoid, and practical portability strategies.
IEC 61131-3portabilitycross-platform
Allen-Bradley DH+ to EtherNet/IP: Network Migration Guide
How to migrate an Allen-Bradley Data Highway Plus (DH+) network to EtherNet/IP. Covers bridge solutions (1756-DHRIO, AN-X2-AB-DHRIO), full migration, MSG instruction conversion, and phased approach.
Allen-BradleyDH+Data Highway Plus
PLC-5 vs. ControlLogix: Key Instruction Set Differences
The most important instruction set differences between PLC-5 and ControlLogix that affect migration. Block Transfers, indirect addressing, PID, ASCII handling, and data types.
Allen-BradleyPLC-5ControlLogix
PLC-5 to ControlLogix Migration: Complete Guide
Complete guide for migrating Allen-Bradley PLC-5 programs to ControlLogix. Covers software conversion, hardware replacement, network migration (DH+ to EtherNet/IP), I/O mapping, and common pitfalls.
Allen-BradleyPLC-5ControlLogix
SLC 500 to CompactLogix: Step-by-Step Conversion
Step-by-step guide for converting Allen-Bradley SLC 500 programs to CompactLogix using Studio 5000. Covers the Logix Designer Export, tag cleanup, I/O remapping, and post-conversion testing.
Allen-BradleySLC 500CompactLogix
Industry Insights(16)
Business cases, ROI analysis, end-of-life planning, and strategic decisions for automation managers.
Pillar Guide
Machine Directive & CE Marking After PLC Migration
Does replacing a PLC require a new CE assessment? When a PLC migration triggers the "substantial modification" clause, what the new EU Machinery Regulation 2023/1230 changes, and how to stay compliant.
·10 min readCE markingmachine directivemachinery regulation
AI in Industrial Automation: Beyond the Hype
An honest assessment of where AI actually delivers value in industrial automation today, where it is still hype, and what plant operators should focus on. Predictive maintenance, code analysis, quality inspection, and the role of PLCs in an AI-driven future.
AIartificial intelligenceindustrial automation
Why Your PLC Code Is Your Most Undervalued Asset
Your PLC code contains decades of process knowledge worth millions — yet it appears nowhere on the balance sheet. Why industrial automation code deserves to be treated as a strategic business asset, and what happens when it is not.
PLCcodeasset
PLC Obsolescence: The Spare Parts Crisis in Industrial Automation
The PLC spare parts crisis explained: Siemens S5 (EOL 2020), S7-300 (production stopped Oct 2025), and what plant operators must do now. Lifecycle timelines, pricing trends, and mitigation strategies.
PLCobsolescencespare parts
5 Signs Your PLC System Needs an Urgent Upgrade
Five concrete warning signs that your PLC system has become a liability. Each sign with real-world consequences and what to do about it. For plant managers and operations leaders.
PLCupgradesigns
PLC Migration ROI: How to Build the Business Case
How to calculate PLC migration ROI and build a convincing business case. Covers cost savings, risk reduction, productivity gains, and a ready-to-use calculation framework.
PLCmigrationROI
More Articles(6)
Additional guides and resources.
Pillar Guide
PLC Memory Optimization: Reducing Data Block Usage
Practical techniques for reducing PLC memory usage on S7-300/400 where memory is limited. Covers DB optimization, marker cleanup, dead code removal, and string handling.
·8 min readPLCmemoryoptimization
Mitsubishi A-Series to iQ-R Migration Guide
Overview of migrating Mitsubishi MELSEC A-series PLCs to the iQ-R platform. Covers software conversion (GX Works2/3), hardware changes, network migration (MELSECNET to CC-Link IE), and common pitfalls.
MitsubishiA-seriesiQ-R
Schneider Modicon to M580: Migration Overview
Overview of migrating Schneider Electric Modicon Quantum and Premium PLCs to the M580 ePAC. Covers the Unity M580 Application Converter (UMAC), hardware mapping, and EcoFit modernization services.
Schneider ElectricModiconQuantum
RSLogix 500 to Studio 5000: Program Conversion Guide
Detailed guide to the software conversion process from RSLogix 500 to Studio 5000 Logix Designer. Covers the Logix Designer Export tool, Project Migrator, file preparation, and post-conversion cleanup.
RSLogix 500Studio 5000conversion
Common PLC Programming Mistakes and How to Fix Them
The 10 most common PLC programming mistakes found in industrial plants. Each mistake with explanation, real-world consequence, and fix. Covers S5 and S7.
PLCprogrammingmistakes
PLC Code Review Best Practices for Industrial Plants
How to conduct a systematic PLC code review in an industrial plant. Covers what to check, how to prioritize, common issues found, and a review checklist.
PLCcode reviewbest practices