Solar tracking system

Description
This SCL function block, FB_LichtNachfuehrung, controls the tracking of a solar panel based on the light difference between two sensors. It integrates emergency stop safety, manual control with priority, and an HMI status display. It runs in the Siemens TIA Portal.

Note: All modules are designed exclusively as a learning and optimization basis and are not approved for live operation. System modules, in particular, must be finally tested and commissioned by qualified personnel before productive use.

How it works

1. Emergency stop active → both motors off, alarm on, HMI “EMERGENCY STOP”, RETURN
2. Hand buttons pressed + limit switch free → manual travel left/right, HMI “Hand: Left/Right/Stop”, RETURN
3. Automatic_On active → Δ = Light_East – Light_West
4. |Δ| ≤ Tolerance → Motor off, HMI “Optimal”
5. Δ > Tolerance → Motor_left on, HMI “Auto: Left”
6. Δ < –Tolerance → Motor_right on, HMI “Auto: Right”
7. Limit switch reached → Stop motor, HMI “Limit reached”

Technical details
• Inputs: #EmergencyStop, #Hand_left, #Hand_right, #Automatic_On, #Light_East, #Light_West, #End_East, #End_West
• Outputs: #Motor_left, #Motor_right, #Alarm, #StatusText_HMI
• Internal variable #Diff, comparison with adjustable #Tolerance
• Priority: Emergency Stop → Manual → Automatic (each via RETURN)
• Sequence control via IF/ELSIF

Possible applications
• Tracking of photovoltaic and solar thermal modules
• Retrofit of existing systems to increase efficiency
• Research laboratories and demonstration facilities
• PLC training on tracking and safety logic

compatibility
Siemens S7-1200 & S7-1500, TIA Portal ≥ V13 (recommended V16+ for PLCSIM & HMI)

Scope of delivery
.scl file with input/output declarations, variables, tolerance settings, and comments; download link immediately after purchase

Support
Adaptation to other sensor layouts, wind measurement, extended HMI displays or logging on request via shop message/email.