LConSMC LCON_DIAM_CALC_MODE_DIVISION Configuration Guide

LConSMC Winder Library Overview

The Library Continuous Strip Material Control (LConSMC) is the Siemens standard function library used to compute and control winder diameter, tension, and speed in SIMOTION and SINAMICS-based strip processing machines. It is delivered as a reusable library block set in SIMOTION SCOUT (and importable in TIA Portal for SIMOTION targets) and is the recommended starting point for unwind/rewind stations in foil, paper, wire, cable, and metal-strip applications.

The library exposes a set of data blocks and a user-defined tag table (LConSMC_Tags) that parameterize the winder. The most critical calculation performed by the library is the diameter calculation, because every downstream function (tension control, taper tension, speed ratio, dancer compensation, torque pre-control) depends on an accurate reel diameter. Diameter is computed by one of several selectable diameter calculation modes, and the mode is selected through the constant tag LCON_DIAM_CALC_MODE_DIVISION.

According to the official LConSMC V3.5.4.25 Tutorial Winder 1 Seed Project documentation, the library provides at least the following output structures for diagnostic purposes:

• winderDiag of type LConSMC_typeWinderDiag — comprehensive diagnostic data of the winder (current mode, status bits, error codes, internal states).
• winderDiameter of type LReal — the live diameter value that the rest of the application must read.

Tag Provenance and the LConSMC_Tags Constants Table

The tag LCON_DIAM_CALC_MODE_DIVISION does not appear in the data block instances of the winder FB; it is a library constant. Constants in LConSMC are surfaced to the engineer through a dedicated user tag table that the library creates on import.

To inspect or change the value:

1. In the SIMOTION SCOUT project navigator, expand the controller node.
2. Open PLC Tags > Libraries > LConSMC_Tags.
3. Open the child element LConSMC_Tags Table (the constants table compiled by the library import).
4. Filter or scroll to the user-constants area. The diameter calculation mode is exposed as LCON_DIAM_CALC_MODE_DIVISION.

When the table is opened in SCOUT, the constant has the structure shown below.

Diameter Calculation Modes in LConSMC

LConSMC supports multiple winder diameter algorithms. The mode constant selects between them. The numeric values and the behavior for each mode (as observed in field installations of LConSMC V3.4 and newer) are summarized below.

The division name in LCON_DIAM_CALC_MODE_DIVISION reflects the legacy naming for Mode 0 (division of pulses). In current LConSMC releases, setting the constant to a value that does not match Mode 1 (Thickness) returns the library to the division / encoder-ratio path.

LCon_TypeDiamConfig Data Block Structure

The library exposes the configuration data type LCon_TypeDiamConfig. This is the structure that must be populated by the user program and handed to the LCon FB instance. Its principal members are listed below.

The 57.296 Default Scale Factor

The default windingShaftFeedbackScal = 57.296 observed in LCon_TypeDiamConfig equals 180/π (≈ 57.29577951). This is the radian-to-degree conversion factor. It appears in the default scaling because the most common configuration in LConSMC's reference winders is a winder shaft feedback in degrees per encoder cycle that the library needs to convert to a linear-diameter ratio.

The scaling relationship is:

D = (V_line / ω_shaft) × (windingShaftFeedbackScal / 2π) × K_gear

where ω_shaft is the shaft feedback expressed in revolutions per unit time. Substituting the default 57.296:

windingShaftFeedbackScal / 2π = 57.29577951 / (2 × π) = 9.5493

This 9.5493 coefficient is the canonical conversion from 1/min (rpm) to rad/s. The 57.296 default therefore corresponds to a default unit system in which the shaft feedback is delivered in rpm and the diameter calculation is expressed in millimeters with a 1:1 gear ratio. If your machine uses a different unit system (e.g., 1/s, m/s, µm), you must re-derive and overwrite windingShaftFeedbackScal.

Configuring Mode 1 (Thickness Mode) for Sensorless Winders

Mode 1 is the correct choice when the machine has no line encoder and no shaft encoder, only a drive-side speed signal (e.g., the SINAMICS actual speed of the winder motor and a virtual line axis built from a master line drive). In this mode the diameter is integrated from the stored material thickness and the number of turns the winder has rotated since diameterInit.

Configuration values to set when using Mode 1 (Thickness):

1. In the LConSMC_Tags user-constants table, leave LCON_DIAM_CALC_MODE_DIVISION at any value that does not select Mode 0 (Division). The exact value depends on library release; in V3.5.4.25, Mode 1 is selected when the constant is 1. Verify the active value in winderDiag.diameterMode after first download.
2. Populate LCon_TypeDiamConfig.thickness with the actual material thickness in mm (or µm, consistent with the diameter unit).
3. Populate LCon_TypeDiamConfig.diameterInit with the empty-core diameter (or current diameter if hot-starting a partly wound reel).
4. Set LCon_TypeDiamConfig.windingShaftFeedbackScal to the actual feedback scaling of your winder shaft (not necessarily 57.296). For a SINAMICS drive with feedback in 1/min and the diameter expressed in mm, the library accepts 57.296 unchanged; for any other unit system, recompute.
5. Set minDiameter and maxDiameter to the mechanical limits of the reel (typically empty core and full reel).
6. Wire the winder drive's actual velocity into windingShaftFeedback via the TO axis. Even in sensorless Mode 1 the shaft feedback is used as a sanity check.

Input Signal Mapping (shaftSpeed, lineFeedback, windingShaftFeedback)

The three speed signals come from physically different sources depending on the machine layout. The table below shows the canonical mapping for a sensorless unwind/rewind configuration with SINAMICS S120 drives and a SIMOTION D controller.

For a sensorless unwind/rewind (no physical line encoder, no physical shaft encoder), both lineFeedback and windingShaftFeedback are sourced from the corresponding drive actualVelocity values. The LCon FB will tolerate this; cross-checking of the two values against the diameter integration is performed internally and surfaces in winderDiag.

Step-by-Step Configuration Procedure

The following procedure brings up a Mode 1 (Thickness) winder in a sensorless configuration using LConSMC V3.4 or newer.

1. Verify the library version. In SCOUT open Libraries > LConSMC > Properties > Version. Confirm V3.4 or newer.
2. Open the user-constants table. Navigate to PLC Tags > Libraries > LConSMC_Tags, open the LConSMC_Tags table, and locate LCON_DIAM_CALC_MODE_DIVISION. Set the value to 1 for Mode 1 (Thickness). Compile and download.
3. Create the configuration instance. Declare an instance of LCon_TypeDiamConfig in the user program (e.g., dbDiamConfig). Initialize it in the startup OB.
4. Populate the data block. In the startup logic, set:

   // dbDiamConfig members
   dbDiamConfig.diameterInit          := 0.0;        // mm — empty core
   dbDiamConfig.thickness             := 0.050;      // mm — material thickness
   dbDiamConfig.minDiameter           := 75.0;       // mm
   dbDiamConfig.maxDiameter           := 600.0;      // mm
   dbDiamConfig.windingShaftFeedbackScal := 57.296;  // 180/pi, only valid for rpm-to-rad
   dbDiamConfig.shaftSpeed            := 0.0;        // updated cyclically
   dbDiamConfig.lineFeedback          := 0.0;        // updated cyclically
   dbDiamConfig.windingShaftFeedback  := 0.0;        // updated cyclically

5. Wire the input signals. In the cyclic OB, copy the TO axis velocities into the data block:

   dbDiamConfig.shaftSpeed           := winderAxis.actualVelocity;
   dbDiamConfig.lineFeedback         := lineAxis.actualVelocity;
   dbDiamConfig.windingShaftFeedback := winderAxis.actualVelocity;

6. Call the LCon FB with the data block reference and read the diameter from the FB's winderDiameter output.
7. Download and run. Observe winderDiameter in the watch table. After one full revolution the diameter must have increased by exactly 2 × thickness.

Diagnostic Tags and Verification

After download, perform the following verification steps to confirm Mode 1 is active and the diameter is integrating correctly.

Troubleshooting Matrix

FAQ