Enabling Faceplate Setpoint Operation in Local Mode for MotSpdCL in SIMATIC PCS 7 APL V8.2 SP2 (Feature2.Bit6)

In SIMATIC PCS 7 Advanced Process Library (APL), the variable-speed motor block MotSpdCL historically disabled operator setpoint modifications from the WinCC faceplate whenever the motor operated in Local mode (LocalAct = 1). Starting in PCS 7 V8.2 with APL V8.2 SP2, Siemens introduced an explicit feature bit: Feature2.Bit6 ('Enable operator setpoint operation in local mode'). By setting Feature2.Bit6 = 1 in the CFC chart and upgrading faceplates, qualified operators with standard authorization can adjust the motor speed setpoint directly from the faceplate while the drive runs in Local mode.

APL Operating Modes and Local Mode Setpoint Tracking Architecture

In SIMATIC PCS 7 Advanced Process Library (APL), motor and drive control blocks (such as MotSpdCL FB 1854) support four distinct operating modes:
- Automatic Mode (AutoAct = 1): Setpoints and start/stop commands are driven by automated sequence logic (CFC/SFC).
- Manual Mode (ManuAct = 1): Setpoints and commands are operated by control room personnel via the WinCC faceplate.
- Out of Service (OosAct = 1): Actuator is passivated for maintenance.
- Local Mode (LocalAct = 1):
* Control is transferred to a local control station, field pushbuttons, or a local Variable Frequency Drive (VFD) keypad near the physical motor.
* Parameter LocalSetting (1 to 4) determines how commands and setpoints are routed.
* In classic APL implementations, Local mode strictly prohibited operator setpoint adjustments from the WinCC faceplate by design, enforcing that all local speed adjustments must originate from local physical potentiometer signals (SP_Ext) or tracking variables (SP_Trk).

Evolution of Local Setpoint Operation - Pre-V8.2 SP2 vs V8.2 SP2

The strict prohibition of faceplate setpoint entry in Local mode created operational bottlenecks in plants where local field stations possessed start/stop pushbuttons but lacked dedicated speed reference entry devices:
1. Pre-V8.2 SP2 Workarounds:
- Engineers had to construct custom external switching logic in CFC:
* Using an analog selector block (e.g. SelA02In) connected to input SP_Ext.
* Or configuring LocalSetting = 3 or 4 with complex tracking logic (SP_Trk).
2. The V8.2 SP2 Enhancement:
- In response to customer requests, Siemens released AP Library V8.2 SP2.
- The update expanded the Feature2 double-word parameter, introducing:
text Feature2.Bit6: The operator can also change the setpoint via the faceplate in local mode
- When this bit is active, the faceplate setpoint input field remains unlocked and editable during Local mode, allowing operators in the control room to adjust speed references while field technicians control starting and stopping locally.

Configuring Feature2.Bit6 and Upgrading APL Block Types

To enable local setpoint entry on MotSpdCL:

Verify APL Library Level:
- In SIMATIC Manager, check Help > About SIMATIC Manager > Display > Installed Software.
- Confirm that PCS 7 Advanced Process Library is updated to at least V8.2 SP2 (or PCS 7 V9.0+).
Update Block Types in CFC:
- Open the Master Data Library and copy the updated MotSpdCL (FB 1854) from the APL V8.2 SP2 library.
- In SIMATIC Manager, open any CFC chart.
- Select Options > Block Types, select MotSpdCL, and click Update Block Types.
Parameterize Feature2 in CFC:
- Open the CFC chart containing the MotSpdCL instance.
- Locate the input pin Feature2:
- Expand the DWORD structure to individual bits.
- Set Bit 6 to 1 (TRUE).
- Alternatively, write the hexadecimal bitmask directly into Feature2 (e.g. 16#00000040 if other Feature2 bits are zero).
Compile and Download:
- Execute Chart > Compile > Changes Only.
- Execute PLC > Download > Changes Only in RUN.
- Compile and download the WinCC OS project to update faceplate scripts (@pg_MotSpdCL.pdl).

MotSpdCL Local Mode Setpoint Control Comparison Table

The following table contrasts setpoint behavior before and after APL V8.2 SP2:

Feature / BehaviorPre-V8.2 SP2 BaselineAPL V8.2 SP2+ with Feature2.Bit6 = 0APL V8.2 SP2+ with Feature2.Bit6 = 1Faceplate Setpoint Field in Local ModeDisabled / Grayed outDisabled / Grayed outActive / Fully EditableSetpoint Source in Local ModeExternal pin (SP_Ext) or TrackingExternal pin (SP_Ext) or TrackingFaceplate internal setpoint (SP_Int)Required CFC Workaround LogicManual selector blocks (SelA02In)Manual selector blocks (SelA02In)Zero external logic requiredOperator Authorization LevelN/A (Locked out)N/A (Locked out)Level 5 (Process controlling)Download Impact to CPUN/AChanges in RUNChanges in RUN

Verification

To confirm that local setpoint adjustment is operational:
1. Open the CFC chart containing MotSpdCL in test mode. Verify that Feature2.Bit6 = TRUE.
2. In WinCC Runtime, open the MotSpdCL faceplate.
3. Switch the motor to Local Mode (LocalAct = 1). Confirm that the faceplate header displays the hand/local indicator.
4. Click the Setpoint input field:
- Confirm that the setpoint entry keypad/dialog opens.
- Enter a new speed reference (e.g. 1200.0 RPM) and click Apply.
5. Verify that:
- The setpoint value updates immediately on the faceplate and in the CFC block output SP_Out.
- The VFD drives the physical motor to 1200 RPM while remaining under local field start/stop control.

Limitations and Operational Precautions

When permitting remote setpoint operation in Local mode:
1. Safety Standards Compliance: In many industrial jurisdictions (EN ISO 13849 / OSHA), Local mode implies local machinery safety where a field technician is performing visual maintenance. Changing drive speed from a remote control room while personnel are near the equipment can create severe mechanical hazards. Conduct a formal risk assessment before enabling Feature2.Bit6.
2. Local Potentiometer Conflicts: If the physical field panel is equipped with an analog potentiometer wired to SP_Ext, enabling Feature2.Bit6 will cause setpoint fighting unless internal/external setpoint switching logic is configured.
3. Faceplate Update Mandatory: Simply changing Feature2.Bit6 in CFC without updating the WinCC faceplate picture files (@pg_MotSpdCL.pdl) will leave the visual field locked, as legacy faceplate scripts enforce hardcoded disable states.

Engineer FAQ

Can I enable local setpoint operation on standard MotL or VlvL blocks?

No. Standard MotL and VlvL blocks do not have analog setpoints; they control discrete start/stop and open/close states. Feature2.Bit6 applies specifically to variable-speed drive blocks (MotSpdCL and MotSpdL).

What happens if Feature2.Bit6 is 0 and the motor enters Local mode?

The setpoint input field in the WinCC faceplate is disabled, and the block uses either the last setpoint, the tracked speed feedback (SP_Trk), or an external analog input (SP_Ext).

Can setpoint limits (SP_HiLim, SP_LoLim) still constrain local setpoints?

Yes. All standard high and low setpoint limits configured on the block continue to clamp operator entries in Local mode, preventing overspeed conditions.