Configuring PROFINET Module Size for Siemens PLCs

Overview

Historically, Gocator Classic and GoPxL (versions prior to v1.4) standardized on a fixed 800-byte maximum module size for the PROFINET industrial communications protocol. While this aligned with the standard memory limits of most Siemens PLCs, controllers with smaller maximum module limits previously required custom firmware.

To address this, LMI introduced native support for variable PROFINET module sizes starting in GoPxL version 1.5. Users can now select scaled module sizes ranging from 16 bytes to 800 bytes directly within Siemens TIA Portal, optimizing memory usage without custom firmware.

Configuration Steps

Step 1: Update GoPxL Firmware

Ensure your Gocator sensor or PC-based GoPxL Accelerator instance is updated to V1.5.52.78 or newer.

Step 2: Download the GSDML File

Navigate to the GoPxL interface, locate the PROFINET Settings drop-down menu, and download the updated GSDML file. (For detailed protocol specifications, please refer to the PROFINET section of the GoPxL user manual).

Step 3: Install GSDML and Add Device in TIA Portal

1. Open TIA Portal, navigate to Options > Manage general station description files (GSD), and install the downloaded GSDML file.

2. In the Network View, locate the Gocator under the Hardware Catalog and drag it onto the canvas.

3. Connect the Gocator’s PROFINET port to your PLC.

Step 4: Configure the Module Size

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1. Double-click the Gocator icon in the Network View to open its Device Overview.

2. In the Hardware Catalog on the right, expand the Gocator submodules (Control, Status, and Measurements).

3. Under the Measurements folder, select your preferred byte size option (e.g., 16, 64, 256, or 800 bytes).

4. Drag and drop the selected module into Slot 3 of the Device View table.

Step 5: Align GoPxL Outputs with PLC Limits

Return to the GoPxL interface and configure your outputs to ensure the total data frame does not exceed the limit allocated in TIA Portal.

Example: If a 256-byte module is selected in TIA Portal, the final data source address plus the byte length of that last measurement must be less than or equal to 256 bytes.