Troubleshoot S7-1200 Communication Issue

I need an expert to troubleshoot a communication issue with my Siemens S7-1200 system. The malfunction is related to the PLC program.

Key requirements:
- Expertise in Siemens S7-1200 systems
- Experience with PLC program diagnostics and repair
- Strong problem-solving skills

Ideal Skills:
- Siemens certification
- Background in industrial automation
- Knowledge of communication protocols used with S7-1200

Please provide a detailed approach and timeline with your bids.