Posts tagged "How-To"
13 articles across the Voltrus blog.
This collection brings together every How-To article published on the Voltrus blog. "How to Read Modbus Holding Registers (FC03): A Practical Walkthrough", "How to Write Modbus Registers: FC06, FC16, and Coils FC05/FC15", "How to Read Allen-Bradley Tags Without RSLinx or FactoryTalk" — each one is a practical, hands-on guide written for engineers and system integrators. Whether you are choosing between protocols, troubleshooting a connection, or planning an integration, these articles cover the concepts, the trade-offs, and the step-by-step details you need.
How 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 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 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 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 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 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 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 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.
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