WinCC Flexible Object Movement Animation with Sensor Stop Logic

1. Application Overview

This reference describes how to drive a continuously moving graphic object on a Siemens WinCC Flexible runtime panel so that the object travels horizontally, freezes the instant a digital sensor input becomes active, and resumes its trajectory once the sensor releases. The pattern is reusable for any indication where a process flag should pause a visual cue without affecting the underlying PLC state machine: conveyor visualization, dancer position, agitator sweep, valve travel, and similar animation use cases.

Two valid implementation paths are documented:

• Horizontal Movement dynamization - one PLC tag carries a 0..N integer; the HMI object binds its X-coordinate to that tag through the Animation dialog.
• Visibility-stacked layers - three identical objects occupy the same coordinates; tag range windows toggle which layer is visible. Useful when pixel-level motion is not required.

The two paths can also be combined: a moving object (method 1) plus a stationary body that appears only inside a defined range (method 2). Both methods run on WinCC Flexible 2008 SP2 through SP5 and remain valid after project migration to TIA Portal WinCC via the Project Converter.

2. Prerequisites

• WinCC Flexible 2008 SP2 or later (SP5 recommended, last released update per Siemens Entry ID 36435786).
• A supported runtime panel: OP 73 / OP 77, TP 177 / TP 177A, MP 177 / MP 277 / MP 377 or a PC Runtime for offline commissioning. Comfort Panels require TIA Portal WinCC; WinCC Flexible targets the legacy panel line.
• PLC: SIMATIC S7-200, S7-300, S7-400, or LOGO! with an MPI/PROFIBUS/Ethernet connection configured in the WinCC Flexible project.
• STEP 7 V5.5 (for S7-300/400) or STEP 7 Basic / Professional in TIA Portal V13+ (for S7-1200/1500) if you author the PLC code.
• One digital input wired to the sensor and configured in the PLC hardware (HW Config or device configuration).

3. System Architecture and Tag Flow

The PLC owns the position counter; the HMI is a thin display client. Only the integer position and a small set of control bits traverse the bus. This keeps the HMI cycle budget unaffected by motion speed because the counter increment is performed inside OB1 on the PLC, not inside the HMI runtime.

4. PLC Program: Continuous Motion with Sensor Pause

The counter is updated only when the sensor is clear. The simplest implementation uses a cyclic timer (TON) in OB1 that increments an integer every N ms while bRun is true. bRun is the boolean AND of the master enable and the negation of the sensor input.

4.1 SCL for S7-1200/1500 (TIA Portal)

// FB_MoveBlock - tag-driven horizontal animation source
FUNCTION_BLOCK "FB_MoveBlock"
{ S7_Optimized_Access := 'TRUE' }
VERSION : 0.1

VAR_INPUT
    iSensor        : BOOL;    // TRUE = pause motion
    bEnable        : BOOL;    // FALSE = freeze at current pos
    iMaxPos        : INT;     // pixel range upper bound
    iCycle_ms      : INT;     // update period, e.g. 100
END_VAR

VAR_OUTPUT
    oPosition      : INT;     // bind to HMI tag
    oAtMax         : BOOL;    // optional diagnostic
END_VAR

VAR
    statTimer       : TON;
    statPos         : INT := 0;
END_VAR

BEGIN
    // Hold position while sensor is active OR enable is false
    "statTimer".IN := "bEnable" AND NOT "iSensor";
    "statTimer".PT := DINT_TO_TIME(INT_TO_DINT("iCycle_ms"));
    "statTimer"();

    IF "statTimer".Q THEN
        "statTimer".IN := FALSE;
        "statTimer"();

        IF "statPos" >= "iMaxPos" THEN
            "statPos" := 0;              // wrap to start
        END_IF;
        "statPos" := "statPos" + 1;
    END_IF;

    "oPosition" := "statPos";
    "oAtMax"    := ("statPos" >= "iMaxPos");
END_FUNCTION_BLOCK

4.2 Equivalent STL for S7-300/400 (STEP 7 V5.5)

// OB1 - cyclic increment, sensor pause
      A     I    0.0          // sensor NC
      AN    M    10.0         // master enable
      =     M    20.0         // bRun (effective run)

      L     MW   102          // iCycle_ms (e.g. 100)
      SD    T    1            // pulse timer 100 ms

      A     T    1
      A     M    20.0
      JC    INC
      JU    DONE

INC:  L     MW   100          // iPosition
      L     MW   104          // iMaxPos
      >=I
      JC    WRAP
      L     MW   100
      +     1
      T     MW   100
      JU    DONE

WRAP: L     0
      T     MW   100

DONE: NOP   0

4.3 Cycle-Time Selection

The visual smoothness on a 6" panel is acceptable at 80-150 ms per increment; faster updates do not render between screen paint cycles and waste bus bandwidth. Use the table below as a starting point:

5. HMI Tag Configuration in WinCC Flexible

1. Open the project, expand "Tags" in the project tree, double-click to add a new tag.
2. Set Name = HMI_Position, Data type = INT (signed 16-bit, range -32768..32767).
3. In Connection, point to the connection that targets your PLC (e.g., S7-300/400 with address DB1,DBW0 or M100). When using S7-1200/1500 in TIA Portal, use the optimized DB symbol or absolute address %MW100.
4. Set Acquisition cycle to 250 ms (default for slow-changing values; raise to 100 ms if you raise the PLC cycle to match).
5. For the sensor itself, add a tag HMI_Sensor of type BOOL, acquisition 100 ms, so the runtime can also drive a status lamp from the same source if desired.

6. Configuring Horizontal Movement Dynamization

1. Open the screen that holds the graphic (e.g., Screen_1).
2. Insert a rectangle or graphic view (Insert > Simple Objects > Rectangle, or insert an SVG/PNG).
3. Right-click the object, choose Properties > Animations.
4. In the Animations dialog, click Add and select Horizontal Movement (some builds label this Dynamization > Movement Horizontal).
5. Configure:
   • Tag: HMI_Position
   • Source range minimum = 0
   • Source range maximum = 400 (must match PLC iMaxPos)
   • Target range minimum = 0 pixels
   • Target range maximum = 400 pixels (screen width minus object width)
6. Confirm with OK. The object X-coordinate is now animated.

At runtime, the object increments one pixel every PLC cycle (e.g., 100 ms), wraps at iMaxPos, freezes when the sensor tag is TRUE, and resumes when the sensor releases. Because the PLC holds the last value during the pause, the screen does not snap backwards.

7. Alternative: Visibility-Layered Animation

When pixel-accurate motion is unnecessary (e.g., coarse state indication), three layered objects each cover the path and become visible inside a defined range window. This was the originally suggested method in the engineering discussion.

1. Place three identical objects at the same X/Y (stack them in z-order).
2. For each object, open Properties > Animations > Add > Visibility.
3. Configure each Visibility entry with a range tag and limits:

Combine with Horizontal Movement dynamization on Layer_1 only to obtain a moving object that additionally reveals a static body when the counter is inside its window.

8. Edge Detection and Sensor Debounce

Mechanical sensors chatter. Run the input through a debounce block before it gates motion:

// IEC debounce timer, SCL
FUNCTION_BLOCK "FB_Debounce"
VAR_INPUT
    iRaw       : BOOL;
    iTime_ms   : INT := 30;     // 30 ms typical
END_VAR
VAR_OUTPUT
    oStable    : BOOL;
END_VAR
VAR
    statTON : TON;
END_VAR
BEGIN
    "statTON".IN := "iRaw";
    "statTON".PT := DINT_TO_TIME(INT_TO_DINT("iTime_ms"));
    "statTON"();
    "oStable" := "statTON".Q;
END_FUNCTION_BLOCK

Feed oStable into iSensor of the motion FB. For sub-millisecond response on a clean 24 V PNP sensor, set iTime_ms := 5. For mechanical limit switches, use 50-100 ms.

9. Bouncing Motion and Direction Reversal

For true back-and-forth motion (e.g., a shuttle), replace the wrap with a direction flip:

// inside FB_MoveBlock, replace the wrap section:
IF "statPos" >= "iMaxPos" THEN
    "statPos" := "iMaxPos";
    "statDir" := FALSE;       // reverse
ELSIF "statPos" <= 0 THEN
    "statPos" := 0;
    "statDir" := TRUE;        // forward
END_IF;

IF "statDir" THEN
    "statPos" := "statPos" + 1;
ELSE
    "statPos" := "statPos" - 1;
END_IF;

Publish statDir to the HMI as HMI_Direction (BOOL) if you want the sprite to flip horizontally. Drive a graphic view's Mirror property from this tag via Direct connection.

10. Verification and Runtime Commissioning

1. Compile the PLC program and download to the controller. Add the FB instance to a cyclic OB (OB1, OB35, or OB200 for S7-1200/1500).
2. In WinCC Flexible, use Tools > Simulation > Start Runtime with the simulator enabled to verify without a panel.
3. Watch the position tag in the WinCC Flexible tag simulator; force it to 0, then to mid-range, then to iMaxPos. Confirm the object jumps to the correct X-coordinate in each case.
4. Force the sensor input to TRUE in PLCSIM or on the live PLC. The object must freeze at its current pixel position. Force the input back to FALSE; motion resumes from the same pixel.
5. Cycle through the full range at least three times to verify the wrap condition.
6. Confirm that the HMI tag's acquisition cycle is shorter than or equal to the PLC cycle.

11. Migrating the Project to TIA Portal WinCC

When the panel reaches end of life, migrate via the TIA Project Converter (menu Project > Migrate project). Mapping summary:

The PLC SCL in section 4.1 is already TIA-syntax and requires no conversion. The STL in section 4.2 can be auto-translated by the SCL/STL converter built into TIA Portal if you want to consolidate.

12. Troubleshooting Matrix