Sequential Cylinder Control with Two Hand Activation

To achieve sequential operation of two cylinders (Cylinder 1 and Cylinder 2) with two-hand activation and interlocking (never both on simultaneously), you'll need a suitable safety-related control scheme using a Siemens PLC (e.g., SIMATIC S7-1200/1500) and potentially a safety relay. Here's a conceptual approach:

Control Logic Outline

1. Two-Hand Activation: Implement a two-hand control circuit using safety-rated input modules. Both pushbuttons *must* be pressed simultaneously to enable cylinder operation.
2. Interlocking Logic: Use PLC logic to ensure only one cylinder can extend at a time.
   • Cylinder 1 extends only when Cylinder 2 is fully retracted and the two-hand activation is valid.
   • Cylinder 2 extends only when Cylinder 1 is fully retracted and the two-hand activation is valid.
3. Position Sensing: Utilize proximity sensors or limit switches to detect the fully retracted and extended positions of each cylinder. These signals are crucial for the interlocking logic.
4. Safety Considerations: Implement safety functions like emergency stop and monitoring of safety-related signals.

Recommended Resources

• SiePortal: Siemens Safety Integrated - Provides information on safety-related control systems.
• Siemens Industry Online Support: Siemens Industry Online Support - Access to FAQs, manuals, and application examples.
• TIA Portal Documentation: Refer to the TIA Portal documentation for detailed information on configuring safety functions and programming logic.

Disclaimer: This is a general guideline. A proper risk assessment and detailed design by a qualified automation engineer are essential to ensure safety and compliance with relevant standards.

Reading Real-Time Clock (RTC) in LOGO! for Tower Clock Application

To control tower clock dials with LOGO! using the RTC, you can follow these steps:

1. Access RTC Blocks: Utilize the "System" blocks within LOGO!Soft Comfort. Specifically, use the "Read Real Time Clock" (RTC) block. This block provides access to the current hour, minute, and second.
2. Data Conversion: The RTC data will likely be in a format suitable for calculations. You might need to use mathematical blocks (ADD, SUBTRACT, etc.) within LOGO! to convert the hour and minute values into signals suitable for driving your dial control outputs.
3. Output Control: Connect the processed hour and minute signals to appropriate LOGO! outputs. These outputs will control the motors or mechanisms that move the tower clock dials. Consider using pulse outputs or PWM for precise dial movement.
4. Scaling & Mapping: Map the hour and minute values to the range of movement needed for each dial. For example, 0-59 minutes maps to 360 degrees of minute hand rotation.

Additional Resources:

• LOGO! 8 - How to read the real-time clock
• Siemens LOGO! Support Portal

Tip: Consider the direction of rotation for each dial and adjust your logic accordingly.