Blog Archive: July 2026
21 articles published in July 2026.
Everything Voltrus published in July 2026 — "Modbus Function Codes Explained: FC01–FC06, FC15, FC16 (2026 Reference)", "Modbus Addressing Explained: PLC Address vs Protocol Address (No More Off-By-One)", "Modbus Exception Codes Explained: Illegal Function, Data, Address (2026 Troubleshooting)". Practical guides and comparisons for engineers working with industrial automation tools, from protocol explorers to SCADA and HMI.
Modbus Function Codes Explained: FC01–FC06, FC15, FC16 (2026 Reference)
Every standard Modbus function code explained: FC01 read coils, FC03 read holding registers, FC06 write single register, FC16 write multiple. Request/response frame layout, byte order, and when to use each code.
Read articleModbus Addressing Explained: PLC Address vs Protocol Address (No More Off-By-One)
Why Modbus holding register 40001 is protocol address 0. The PLC address vs protocol address off-by-one confusion, the four address ranges, and how to convert between them.
Read articleModbus Exception Codes Explained: Illegal Function, Data, Address (2026 Troubleshooting)
Modbus exception codes 01–08 decoded: Illegal Function, Illegal Data Address, Illegal Data Value, Slave Device Failure. What each exception means, why your master gets it, and how to fix the request.
Read articleTeamViewer Alternative for PLC Remote Access: Why OT Teams Are Switching
TeamViewer puts an always-on graphical backdoor on the OT network. A WireGuard mesh gives the engineer a route to the PLC subnet only — outbound-only, self-hosted, no third-party relay.
Read articleSecure Remote Access to PLC Networks: A Practical Guide for Integrators
Threat model, architecture, ACL design, and a deployment checklist for reaching PLC subnets over a self-hosted WireGuard mesh without exposing the OT network.
Read articleWireGuard vs Traditional VPN for OT Networks: Which Wins in 2026
WireGuard vs IPsec/OpenVPN for OT remote access: performance, audit surface, key management, NAT traversal (DERP), and why WireGuard + Headscale fits industrial sites.
Read articleRemote Access Without Inbound Ports: Outbound-Only OT Connectivity
Opening inbound VPN ports on an OT firewall violates every security baseline. Outbound-only mesh connectivity plus DERP-over-TCP/443 sidesteps it entirely.
Read articleRemote PLC Commissioning: Reach Any Site Without a Plane Ticket
Tunnel into the PLC subnet and run TIA Portal, GX Works, or SoMachine against the local PLC IP at full speed — no screen-share lag, no $5K travel bill per site visit.
Read articleBACnet Objects and Properties: The Object Model Explained
BACnet models every data point as an object with typed properties (Present-Value, Units, Status-Flags). This self-description enables discovery — no external register map needed.
Read articleOPC-UA vs MQTT for Industrial IoT: Which Should You Choose
OPC-UA for rich plant-floor integration and SCADA; MQTT for lightweight multi-site telemetry. Data models, security, bandwidth, and when each protocol wins.
Read articleModbus Float Byte Order Explained: ABCD, DCBA, BADC, CDAB
A 32-bit Modbus float spans two registers and every vendor picks a different byte order. Why your 230 V reading shows as 0.003, and how to cycle the four conventions to fix it.
Read articleSiemens S7 Rack and Slot Addressing: How PLC Routing Works
S7 connections need the right rack and slot (S7-1200/1500: rack 0 slot 0; S7-300: rack 0 slot 2). Get it wrong and you get a connection-refused — here is why and how to fix it.
Read articleMQTT Retained Messages and Last Will: Explained with Examples
Retained messages give new subscribers instant state; Last Will publishes on ungraceful disconnect for offline detection. Concrete topic and payload examples included.
Read articleSCADA for Water and Wastewater: A System Integrator Guide
Remote pump stations, radio/cellular telemetry, DNP3 and Modbus, alarm management for unattended sites — and why lightweight self-hosted SCADA fits thin utility budgets.
Read articleSCADA Historian: Data Logging and Trend Analysis That Actually Helps
A historian stores full-resolution, time-stamped process data — the foundation for troubleshooting, predictive maintenance, and compliance. Build vs buy, and retention strategy.
Read articleModbus TCP Security Risks: Why It Is Not Safe and How to Protect It
Modbus TCP has no authentication, encryption, or integrity — anyone on the network can read and write every register. Segment, firewall, and tunnel it; never expose TCP/502.
Read articleThe Industrial Edge Gateway Stack: What You Actually Need in 2026
An edge gateway needs three things: a protocol-capable agent, a local buffer, and northbound transport. The minimal stack runs in 512 MB — the vendor bloat stack eats 4 GB.
Read articleIgnition vs Node-RED vs Voltrus: 2026 SCADA Comparison
Ignition (powerful, $6K+ modules) for enterprise. Node-RED (free, but not real SCADA) for prototyping. Voltrus (single binary, lifetime license) for the mid-market. Honest side-by-side.
Read articleMobile-Friendly SCADA Dashboards: Monitoring the Plant From Your Phone
Why responsive dashboards matter for on-call engineers, design principles for industrial mobile UIs, and the security rule: never expose SCADA to the public internet.
Read articlePLC vs Microcontroller: When to Use Each in Industrial Projects
A PLC is rugged, deterministic, and supported for a decade. An Arduino is cheap and flexible. Why hobbyist microcontroller builds fail on the factory floor — and when each wins.
Read articlePostgres CLI Tools vs pgAdmin: When the Terminal Wins
pgAdmin is a heavy web UI that is painful over SSH. Terminal Postgres browsers like PostgresTUI start instantly, work natively over SSH, and stay out of your way for quick queries.
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