TcHmiLogixDriver

A Rockwell Automation communcation driver for TwinCAT HMI.

Uses the LogixDriver wrapper for libplctag.NET to communicate via EtherNet/IP to ControlLogix platform PLCs.

Within the TwinCAT HMI framework, this driver supports:

• Connection state monitoring / reconnection
• Tag browsing
• Automatic type and value resolution

For how it works under the hood (symbols, mapping, reads and writes, connections and errors), see the documentation.

Installation

Download the latest .nupkg release, then place it in a nuget offline packages folder (e.g. C:\ProgramData\Beckhoff\NuGetPackages). It will now be availabe to install in your TwinCAT HMI project via the nuget package manager GUI (References -> Packages) or CLI (nuget install TcHmiLogixDriver).

Tag Mapping

The tag browser allows you to map top-level UDTs and arrays, or individual members / elements. What you map decides what gets read from the PLC. Any request that falls under a mapped path is served by one read of that mapped tag.

Example

For instance, take this tag model in the PLC:

Line                 LINE_UDT
├── Speed            REAL
├── Running          BOOL
└── Motors           MOTOR_UDT[4]
    └── [0..3]
        ├── Speed    REAL
        ├── Current  REAL
        └── Faults   DINT

with the following mapped symbols:

Line
Line.Motors
Line.Motors[2].Speed

To serve a binding, the driver walks down a mapping tree along the binding's path and stops at the deepest node it reaches. That node is the tag it reads from the PLC:

Control Binding	Mapped path	Read from PLC
Line.Speed	Line	Line (whole structure)
Line.Motors[0].Current	Line.Motors	Line.Motors (whole array)
Line.Motors[2].Speed	Line.Motors[2].Speed	Line.Motors[2].Speed (single primitive)

Notice that the binding to Line.Speed causes the whole Line structure to be read!

• Map a parent structure or array when the HMI shows many of its members. Every binding under it (Line.Speed, Line.Running, …) is served by a single PLC request.
• Map individual members when you only need a few fields from a large structure or array, so the driver doesn't transfer the whole thing for each request.
• When mappings overlap, the most specific path wins. Line is mapped, but Line.Motors[2].Speed has its own mapping, so bindings for that tag read just that member and not all of Line.

Renaming mapped symbols is not supported in this version. Keep the default name the tag browser assigns (TcHmiLogixDriver.<target>.<path>). The driver builds its mapping tree from those names, so a renamed symbol is left out. Bindings to it then read a larger mapped parent, or fail.

Writes

Writes don't use the mapping tree. The requested path is turned straight into a tag name (Line.Motors[0].Current → Line.Motors[0].Current) and written as is. A structure write must include every member of the structure.

Dependencies

• Beckhoff.TwinCAT.HMI.Server.Engineering >= 14.5.73.0 (22.0.7983)