Conveyor belt with weight detection

Description

This function block precisely sorts conveyed objects by weight —light, heavy, or within the standard range—thus ensuring automated and reliable separation in your system. The code, written in Structured Control Language (SCL), runs directly in the Siemens TIA Portal and is ideal for sorting processes in the food, pharmaceutical, or logistics industries.

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

The control system starts with a safety check : As soon as an emergency stop or stop button is pressed, the entire system stops immediately, all outputs are deactivated and the sequence control jumps back to step 0 .

In automatic mode, the start button activates the conveyor belt. As soon as an object is detected, an edge detector stops the belt – allowing time for the weight measurement .

• In step 1, the controller checks whether the analog weight value is within the valid range .
  If not: Alarm ! – and immediate restart.
• If the value is valid, the logic decides:
• Too easy? ⇒ Switch to EjectionEasy
• Too heavy? ⇒ Switch to Exit Heavy
• Exactly right? ⇒ SignalOK

The selected output remains active for the set eject time , controlled by an IEC timer . After that, all switches reset, the belt starts running again, and the next cycle begins.

Technical details

• Safety logic : Emergency stop & stop button immediately stop the process and reset all actuators
• Edge detection : via rtr trigger for each newly detected object
• FSM control : four clearly defined states (idle, evaluation, hold time, reset)
• Timer-controlled ejection : via TON timer and configurable eject time
• Plausibility check : Weight must be in the range 0…27648 , otherwise error
• Outputs : AusschleusLeicht , AusschleusSchwer , SignalOK , Foerderband – all available as TRUE/FALSE signals

Possible applications

Ideal for:

• Filling and packaging lines in the food or beverage industry
• Quality control by weight in pharmaceutical and chemical production
• Logistics centers where goods are pre-sorted by mass
• Laboratories and training , for practical training of FSM, security and sensor integration

Thanks to the modular structure, you can easily adapt the logic to other measured values (e.g. volume, density) or additional sorting criteria .

compatibility

• Runs on Siemens S7-1200 and S7-1500
• Compatible with TIA Portal from version V13
• For simulation & visualization: TIA V16 or higher , PLCSIM recommended

Scope of delivery

You will receive:

• An .scl file with:

• all entrances and exits
• FSM steps
• Trigger instances
• Timer parameters

• Commented notes in the header for adjusting:

• Weight thresholds
• Eject time
• Security parameters

The download link is available immediately after purchase.

Support

I am happy to help you with:

• fine-tuning the threshold values
• integration into existing control systems
• the extension to include HMI functions

Just write me an email or contact the shop support directly – together we’ll get the most out of your sorting system.