Skip to main content

PLC Programming

Programmable Logic Controller programming, configuration, and troubleshooting for Allen-Bradley, Siemens, and Schneider Electric platforms.

View Our SCADA & Programming Services
Guide

4-20mA Loop Troubleshooting

Step-by-step guide for troubleshooting 4-20mA current loops in industrial instrumentation. Covers loop power verification, transmitter diagnostics, wiring faults, and common failure modes for 2-wire and …

4 min read
Article

Thermocouple and RTD Troubleshooting

Field guide to diagnosing thermocouple and RTD temperature sensor problems. Covers open circuit detection, calibration drift, cold junction compensation, lead wire resistance issues, and sensor …

4 min read
Article

Level Transmitter Calibration and Errors

Troubleshooting level transmitter calibration errors, including radar, ultrasonic, hydrostatic, and float-based level measurement. Covers common error sources, recalibration procedures, and environmental factors affecting accuracy.

4 min read
Article

Pressure Transmitter Drift and Recalibration

Diagnosing and correcting pressure transmitter drift in industrial process applications. Covers drift causes, field calibration procedures, HART diagnostics, and maintenance scheduling for gauge, absolute, and …

3 min read
Article

Flow Meter Accuracy Issues

Diagnosing flow meter accuracy problems across common technologies including magnetic, Coriolis, ultrasonic, vortex, and differential pressure flow meters. Covers installation effects, process condition impacts, and …

4 min read
Guide

VFD Fault Codes and Resolution

Field guide to diagnosing and resolving variable frequency drive (VFD) fault codes. Covers overcurrent, overvoltage, ground fault, overtemperature, and communication faults across major VFD brands …

5 min read
Article

Instrument Air System Troubleshooting

Diagnosing and resolving instrument air system problems that affect pneumatic valve and actuator operation. Covers compressor issues, dryer failures, pressure regulation, air quality, and the …

4 min read
Article

Control Valve Positioner Calibration

Step-by-step guide to calibrating pneumatic and smart valve positioners in industrial control systems. Covers positioner types, auto-calibration procedures, manual calibration, diagnostics, and common problems that …

4 min read
Article

Analog Signal Noise and Grounding Issues

How to identify, diagnose, and eliminate electrical noise on analog signals in industrial control systems. Covers grounding techniques, shielding practices, filtering methods, and common sources …

4 min read
Guide

PLC Fault Diagnosis Checklist

A systematic checklist for diagnosing PLC faults in industrial control systems. Covers hardware diagnostics, I/O module failures, processor faults, communication errors, and power supply issues …

5 min read
Guide

Migrating from Legacy PLCs to Modern Platforms

Migrating from legacy PLCs (PLC-5, SLC-500, S7-300/400, Modicon 984) to modern platforms extends system lifecycle, improves cybersecurity, and unlocks Ethernet communication and modern diagnostics. Successful …

5 min read
Pillar Page

PLC Programming for Industrial Automation

PLC programming is the foundation of industrial automation, using languages defined by IEC 61131-3 to control machinery, processes, and safety systems. Modern PLCs support ladder …

5 min read
Guide

Allen-Bradley ControlLogix Programming Guide

Allen-Bradley ControlLogix is Rockwell Automation's flagship PLC platform, programmed using Studio 5000 Logix Designer. ControlLogix supports all IEC 61131-3 languages, features tag-based addressing with no …

4 min read
Article

Siemens S7-1500 vs Allen-Bradley CompactLogix

The Siemens S7-1500 and Allen-Bradley CompactLogix are the two most widely deployed mid-range PLCs globally. The S7-1500 dominates European and Asian markets while CompactLogix leads …

3 min read
Article

Ladder Logic vs Structured Text vs Function Block

IEC 61131-3 defines three primary PLC programming languages: Ladder Diagram for discrete logic, Structured Text for calculations and algorithms, and Function Block Diagram for continuous …

4 min read
Article

PLC Program Testing and Simulation Best Practices

Thorough PLC program testing before field deployment reduces commissioning time, prevents equipment damage, and improves safety. Testing strategies include offline simulation, hardware-in-the-loop (HIL) testing, factory …

4 min read
Article

PLC-to-SCADA Integration Patterns

PLC-to-SCADA integration connects field-level controllers with supervisory systems for monitoring, data collection, alarming, and remote control. Common integration patterns include OPC DA/UA, native driver connections, …

3 min read
Article

Analog Input Scaling and Calibration

Analog input scaling converts raw PLC input values (typically 4-20 mA or 0-10 V signals) into meaningful engineering units such as PSI, degrees Fahrenheit, or …

4 min read
Article

PID Loop Tuning for Industrial Processes

PID (Proportional-Integral-Derivative) control is the dominant feedback control algorithm in industrial automation, used for temperature, pressure, flow, level, and speed regulation. Effective PID tuning balances …

4 min read
Article

Safety PLC Programming (IEC 61511)

Safety PLC programming implements Safety Instrumented Functions (SIFs) that protect personnel, equipment, and the environment from hazardous process conditions. IEC 61511 defines the lifecycle for …

4 min read
Article

Motor Control Center (MCC) Automation

Motor Control Center (MCC) automation integrates intelligent motor starters, overload relays, and VFDs with PLC control systems using industrial communication networks. Modern intelligent MCCs provide …

4 min read
Article

VFD Integration and Programming with PLCs

Variable Frequency Drives (VFDs) control motor speed by adjusting the frequency and voltage of AC power, enabling energy savings of 20-50% on centrifugal loads. PLC …

4 min read
Article

PLC Data Logging and Historian Integration

PLC data logging captures time-series process data for historical trending, regulatory compliance, production reporting, and root cause analysis. Integration with process historians like OSIsoft PI, …

4 min read
Article

HMI Design Best Practices for Industrial Operators

Effective HMI (Human-Machine Interface) design follows the ISA-101 high-performance principles: gray backgrounds instead of colorful graphics, information hierarchy from overview to detail, limited use of …

3 min read

Questions About PLC Programming?

Our engineers have decades of hands-on experience. Let's discuss your project.

Contact NFM Consulting