Category Archives: PLC Communication

The first thing to understand about transparent mode is that there is no fixed control word bit layout to memorize. The information is not hidden. Under ABB Drives or PROFIdrive, the profile defines how the control word, status word, references and actual values are interpreted. Under Transparent 16 or Transparent 32, the FPBA-01 does not impose that interpretation.… Read More: ACS880 PROFIBUS Transparent Mode: Control and Status Words »

Two profiles. The same drive can use either one over the same network. Even when the configured process-data size is identical, the meaning of the words can change. That is what makes this comparison worth writing down. Nothing visibly breaks when you pick the wrong one. The bus goes green, the PLC exchanges data, the drive accepts a… Read More: PROFIdrive vs ABB Drives Profile: Key Differences »

One parameter decides how your PLC talks to an ACS880 over PROFIBUS. It is 51.05 Profile. Not 51.02. That one is the node address, and it gets confused with the profile setting constantly — including in some vendor quick-start guides that use the label “Protocol/Profile” for 51.02. On an ACS880 with an FPBA-01, node address is 51.02 and… Read More: ACS880 PROFIBUS DP Profiles: How to Choose the Right 51.05… »

Most fieldbuses solve the problem of moving a lot of data between intelligent devices. AS-Interface solves a different one: getting a few bits to and from hundreds of dumb devices, cheaply, without a terminal strip the size of a door. A proximity switch has one bit of information. A solenoid valve needs one bit. Wiring each one back… Read More: AS-Interface (AS-i) Explained: The Yellow Cable Bus »

The 4-20 mA loop normally represents one primary process variable. It has done so since the 1950s, it is understood by every technician alive, and it will outlive most of the protocols competing to replace it. HART’s insight was not to replace it. HART puts a digital signal on top of the analog loop, so the same two… Read More: HART Protocol Explained: Digital Data on a 4-20 mA Loop »

If you have configured Modbus TCP on a CODESYS PLC, you might expect the same device-tree workflow in Beckhoff TwinCAT. It works differently. Although TwinCAT and CODESYS both implement IEC 61131-3 programming languages, TwinCAT uses Beckhoff’s own runtime and engineering environment. Because of that, Modbus TCP configuration is completely different from what CODESYS users expect — you will… Read More: Modbus TCP on Beckhoff TwinCAT: Client and Server Setup »

CODESYS is the runtime that powers a large chunk of the industrial PLC market — WAGO, Phoenix Contact, ABB, Delta, Eaton, Bosch Rexroth, Turck, and many more all use CODESYS underneath their own branded engineering software. The good news for anyone working with Modbus TCP on these platforms: CODESYS has native Modbus TCP support built in. No third-party… Read More: Modbus TCP on CODESYS PLCs: Step-by-Step Configuration »

Every PLC vendor has its own toolchain, but they largely follow the same programming model. That’s because of IEC 61131-3. It defines the programming languages, the data types, and the software architecture that PLCs and their programming tools are built around. The goal is portability — write logic against the standard, and it should carry across platforms with… Read More: IEC 61131-3: The Complete Guide to PLC Programming Languages »

You have a ControlLogix PLC and someone just added a Modbus TCP flow meter to your project. Studio 5000 opens, you look for the “Modbus TCP” option in the module tree… and it is not there. Not in the standard modules. Not in the add-on profiles. Not in the Ethernet configuration. That is because ControlLogix has no native… Read More: Modbus TCP on Allen-Bradley ControlLogix (Studio 5000) »

On an Allen-Bradley controller, “CIP” and “EtherNet/IP” are the same conversation. CIP is the protocol — the object model, the services, the way data is named. EtherNet/IP is CIP running on top of standard Ethernet. When you configure a Rockwell PLC to talk to a drive, a remote I/O block, a camera, or another controller, you’re configuring EtherNet/IP,… Read More: How to Configure CIP (EtherNet/IP) on Allen-Bradley Controllers »