Blog Archive: August 2026
43 articles published in August 2026.
Everything Voltrus published in August 2026 — "Modbus Poll vs Modscan vs Modbus Slave: Which Master Tool to Use", "Modbus TCP vs PROFINET: Choosing the Right Industrial Ethernet", "How to Read Modbus Holding Registers (FC03): A Practical Walkthrough". Practical guides and comparisons for engineers working with industrial automation tools, from protocol explorers to SCADA and HMI.
Modbus Poll vs Modscan vs Modbus Slave: Which Master Tool to Use
Modbus Poll, Modscan, and Modbus Slave compared. Platform support, RTU vs TCP, master and simulator modes, pricing, and which Modbus master tool fits your workflow in 2026.
Read articleModbus TCP vs PROFINET: Choosing the Right Industrial Ethernet
Modbus TCP vs PROFINET compared. Real-time determinism, device discovery, configuration effort, vendor ecosystem, and when to use each industrial Ethernet protocol.
Read articleHow to Read Modbus Holding Registers (FC03): A Practical Walkthrough
How to read Modbus holding registers with function code 03. Slave ID, start address, quantity, the FC03 frame, 16-bit byte order, and 32-bit scaling explained.
Read articleHow to Write Modbus Registers: FC06, FC16, and Coils FC05/FC15
How to write Modbus registers and coils. FC06 write single register, FC16 write multiple, FC05/FC15 coils. Frame layout, exception codes, and safe write practice.
Read articleModbus RTU to TCP Gateway: Bridge Serial Devices onto Ethernet
Modbus RTU to TCP gateway explained. Why bridge RS-485 serial devices onto Ethernet, how a gateway routes TCP requests to RTU slaves, latency, hardware vs software gateways.
Read articleEtherNet/IP vs PROFINET: Rockwell vs Siemens Industrial Ethernet
EtherNet/IP vs PROFINET compared. Rockwell/Allen-Bradley vs Siemens ecosystems, CIP vs PROFINET IO, real-time classes, device description, and which to choose.
Read articleHow to Read Allen-Bradley Tags Without RSLinx or FactoryTalk
Read Allen-Bradley ControlLogix and CompactLogix tags without RSLinx, FactoryTalk, or Windows. How the ENIP session and CIP tag services work, and how to browse and read tags anywhere.
Read articleEtherNet/IP ListIdentity: How Device Discovery Works (UDP 44818)
EtherNet/IP ListIdentity discovery explained. How a broadcast on UDP 44818 finds every CIP device, what the Identity reply contains, and how to browse devices on macOS.
Read articleCIP Explicit vs Implicit Messaging: When to Use Each
CIP explicit vs implicit messaging compared. Explicit (TCP 44818, request-response, tag reads) vs implicit (UDP 2222, cyclic I/O, RPI). Use cases, overhead, and when each wins.
Read articleEtherNet/IP Port 44818 Explained: TCP, UDP 2222, and Firewall Rules
EtherNet/IP port 44818 explained. TCP 44818 for explicit messaging, UDP 2222 for cyclic I/O, UDP 44818 for ListIdentity discovery. Firewall rules and security.
Read articleDNP3 vs Modbus for SCADA: Which Protocol for Utilities
DNP3 vs Modbus for SCADA compared. Event-driven reporting, timestamps, class polling, multi-drop vs point-to-point, and which fits utilities and water/wastewater.
Read articleDNP3 vs IEC 60870-5-104: Power Utility Protocols Compared
DNP3 vs IEC 60870-5-104 compared. The two dominant power-utility SCADA protocols. Addressing, transport, event model, region, and which to choose for substations.
Read articleHow to Simulate a DNP3 Outstation for Testing
How to simulate a DNP3 outstation. Why you need a simulator, configuring addressing and points, generating Class 0/1/2/3 events, and testing a DNP3 master without field hardware.
Read articleDNP3 Class 0, 1, 2, 3 Explained: Event Polling Strategy
DNP3 Class 0, 1, 2, 3 explained. Class 0 is a full snapshot; Classes 1-3 are prioritized event backlogs. How utility masters poll by class to retrieve only what changed.
Read articleDNP3 Select-Before-Operate (SBO): Safe Control Outputs
DNP3 Select-Before-Operate explained. Why SBO guards critical controls, how the select-then-operate two-step works, select timeouts, and direct operate for non-critical points.
Read articleOPC UA vs OPC Classic (DA): Why the Upgrade Matters
OPC UA vs OPC Classic (DA) compared. Platform-independent transport, built-in security, rich information model, and why migrating from COM-based OPC DA to OPC UA matters.
Read articleOPC UA Information Model: Nodes, Objects, and the Address Space
OPC UA information model explained. Nodes, objects, variables, type system, the address space, references, and companion specifications. How UA self-describes data.
Read articleOPC UA Security: Certificates, Encryption, and Auth Setup
OPC UA security explained. Security modes (None, Sign, SignAndEncrypt), security policies, X.509 certificates, mutual authentication, trust lists, and secure setup.
Read articleHow to Browse an OPC UA Server Address Space
How to browse an OPC UA server address space. Connect, get endpoints, open a session, browse nodes by reference, find variables, and read values on any platform.
Read articleOPC UA Subscriptions and Monitored Items: Subscribe to Variable Changes
OPC UA subscriptions and monitored items explained. Publishing interval, sampling, data-change filters, and why subscribe beats poll for live monitoring.
Read articleSiemens S7-1200 vs S7-1500: Which PLC for Your Project
Siemens S7-1200 vs S7-1500 compared. Performance, memory, I/O count, motion, safety, PROFINET, price, and which Siemens PLC fits small machines vs large process lines.
Read articleS7 Protocol vs OPC UA for Siemens PLCs: Direct or Standardized
S7 protocol vs OPC UA for Siemens PLCs compared. Native direct access vs the cross-vendor standard, performance, security, setup, and when to use each.
Read articleHow to Read a Siemens S7 Data Block (DB) Over the Network
How to read a Siemens S7 data block. DB number and offset addressing, data types, the rack/slot connection, enabling PUT/GET, and reading S7-1200/1500 DBs.
Read articleHow to Enable PUT/GET on S7-1200/1500 (and Why Siemens Disables It)
How to enable PUT/GET on Siemens S7-1200/1500. Why Siemens disables it by default, the TIA Portal steps, the security trade-off, and safer alternatives like OPC UA.
Read articleSiemens S7 vs Modbus TCP: Native PLC Access vs Universal Register
Siemens S7 vs Modbus TCP compared. Native data-block access vs universal register addressing, typed vs flat data, where each wins, and how Siemens sites run both.
Read articleBLE GATT Services and Characteristics Explained: How Every BLE Device Is Structured
The GATT data model end to end: ATT vs GATT, the Profile, Service, Characteristic, Descriptor hierarchy, UUID formats, characteristic properties, the CCCD, ATT operations, and a full byte-level walk-through of the Heart Rate Service.
Read articleiBeacon vs Eddystone: BLE Beacon Formats Compared
Byte-level layout of iBeacon and Eddystone (UID, URL, TLM frames), how proximity is estimated from RSSI and why it is noisy, plus how to decode both formats from raw advertising packets on macOS.
Read articleBLE Pairing and Bonding: Security Explained
Pairing vs bonding, LE Legacy vs LE Secure Connections (ECDH P-256), the four association models, the STK/LTK key hierarchy, AES-CCM encryption, IRK-based privacy, Security Mode 1 levels, and how to debug auth failures on macOS.
Read articleModbus RTU Over Serial: How It Works on RS-485
A byte-level breakdown of Modbus RTU on RS-485: frame structure, CRC-16 with polynomial 0xA001, function codes, 3.5-character inter-frame timing, and a worked FC03 request/response you can read off the wire.
Read articleRS-485 Termination and Biasing: Why Your Serial Bus Is Unreliable
Why RS-485 buses produce CRC errors and garbage bytes: differential signalling, 120-ohm end termination, fail-safe bias resistor math, unit-load counting, and daisy-chain-only topology.
Read articleMQTT Topic Design: Best Practices for Naming and Wildcards
MQTT topic naming rules, forward-slash hierarchy, the + and # wildcards, shared subscriptions, ACL security, and the anti-patterns that bite teams in production.
Read articleMQTT vs HTTP for IoT: Which Protocol Should You Use
MQTT vs HTTP for IoT — publish/subscribe vs request/response, 2-byte headers vs hundreds, push vs poll, QoS guarantees, and when to use each protocol.
Read articleOPC UA Companion Specifications: How UA Models Real Industries
How OPC Foundation collaborations with industry bodies (VDMA, PLCopen, VDW, BACnet) add typed, domain-specific information models so multi-vendor equipment interoperates without per-vendor register maps.
Read articleOPC UA vs Modbus TCP: Which Industrial Protocol to Choose
Modbus TCP and OPC UA compared on data model, security, discovery, transport, scalability, and best-fit use cases — plus the gateway-aggregation pattern most plants actually run.
Read articlePROFINET vs S7 Communication: What's the Difference
PROFINET IO and S7 communication are not competing protocols — they coexist on every Siemens controller. PN-IO is the deterministic fieldbus for cyclic I/O; S7 is the acyclic read/write protocol over TCP port 102. Ports, RFC 1006, RT/IRT timing, GSDML, and macOS tooling explained.
Read articleMQTT vs Direct Database Writes from IoT Devices: Why the Broker Wins
Why IoT devices that INSERT directly to Postgres, MySQL, or SQL Server break at scale — connection limits, schema coupling, no offline buffering, credential sprawl — and why an MQTT broker feeding a single ingest bridge is the architecture that survives a field fleet.
Read articleBLE Advertising Packets Explained: How Devices Broadcast Without Connecting
BLE advertising packets explained: the 31-byte payload, AD structures, flags, UUIDs, manufacturer data, scan response, and how to decode raw advertising data on macOS.
Read articleMQTT Keep Alive Explained: What It Is, How to Tune It, and Why Clients Disconnect
MQTT keep alive explained: the CONNECT packet field, the 1.5x timeout rule, PINGREQ/PINGRESP, how brokers detect dead clients, and how to choose the right interval for IoT devices.
Read articleEtherNet/IP RPI Explained: Requested Packet Interval, CIP I/O, and How to Tune It
EtherNet/IP RPI (Requested Packet Interval) explained: the timing of CIP implicit I/O, how RPI differs from the CIP connection timeout, and how to choose and tune RPI values for Allen-Bradley PLCs.
Read articleModbus 32-Bit Integer Data Types: Registers, Byte Order, and Scaling Explained
How Modbus handles 32-bit integers: two registers per value, word order (high word first vs low word first), signed vs unsigned, register pairs, and scaling examples for energy meters and drives.
Read articleVoltrus Gateway vs Kepware: A Cross-Platform OPC Gateway Alternative
Kepware is the default — a Windows-only, licensed OPC server with per-tag pricing. Voltrus Gateway is a cross-platform, self-hosted Rust binary exposing one typed gRPC API across six protocols, one-time per host. An honest feature-by-feature comparison.
Read articleOne Typed gRPC API for Every Industrial Protocol
Why one typed gRPC surface beats a separate client for Modbus, OPC UA, EtherNet/IP, S7, DNP3, and BACnet. Type-preserving values, server-streamed subscriptions, and a single canonical implementation.
Read articleModbus, OPC UA & EtherNet/IP in One Binary: Unifying Six Protocols
How one Rust binary drives Modbus TCP, OPC UA, EtherNet/IP (CIP), Siemens S7, DNP3, and BACnet/IP behind a single API. The mt-* engines, read/write/subscribe parity, and why protocol bugs get fixed once.
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