Freelance Siemens S7-1200 PLC Automation Engineer Required | Scientific & Special-Purpose Equipment

We are looking for an experienced freelance industrial automation engineer to support the development and implementation of PLC control software for a special-purpose scientific/laboratory equipment system .

The equipment involves a controlled, multi-stage process with vacuum, gas flow, pressure, power, temperature, utility monitoring, and other process parameters.

We are looking for someone capable of developing a structured, reliable, and maintainable PLC application , rather than simply programming basic machine I/O and sequencing.

Mandatory Requirements

Location The freelancer must be physically located in the Mumbai suburban area and be available for on-site work when required.

This may include in-person meetings, hardware testing, integration, calibration, troubleshooting, and commissioning support.

Remote-only applicants or freelancers located outside Mumbai suburbs will not be considered.

Confidentiality & NDA The selected freelancer will be required to sign a Non-Disclosure Agreement (NDA) before receiving access to detailed technical documentation, process information, software architecture, communication details, or other confidential project materials.

Only freelancers willing to sign the NDA should apply.

Scope of Work The selected engineer will work with the following hardware:

- Siemens SIMATIC S7-1200 CPU 1212C G2
- Siemens SM1231 Analog Input module
- Siemens SM1222 Digital Output module
- Siemens CM1241 RS485 communication module
- TIA Portal

The PLC software should follow a modular, structured, and scalable architecture .



Process Sequence / State Machine

Develop a structured, recipe-driven process sequence covering multiple stages, including:

- Pre-start and system readiness checks
- Vacuum/process preparation stages
- Optional pressure conditioning cycles
- Process initiation and verification
- Controlled multi-parameter ramp-up
- Process stabilization
- Controlled introduction and ramping of process gases
- Long-duration process operation
- Controlled normal shutdown and ramp-down
- Emergency shutdown sequence

• Fault handling and appropriate reset/recovery logic The process should be implemented using a structured state machine , rather than a large collection of independent timers and Boolean logic.

Deliverables The selected freelancer will be expected to provide:

- Complete TIA Portal PLC project
- Structured and documented source code
- Modular PLC program architecture
- Main process state machine
- Reusable generic ramp control FB
- Recipe/parameter management structure
- Interlock and alarm handling
- Normal shutdown sequence
- Emergency shutdown sequence
- I/O mapping and abstraction
- RS485/device communication implementation
- Source code with meaningful comments
- Basic technical documentation
- Remote and/or on-site support during calibration,



testing and commissioning, as mutually agreed

All project-specific source code, PLC program files, documentation, and other deliverables developed under the engagement should be handed over as part of the project deliverables.

Required Experience

Please apply only if you have solid experience with:

- Siemens S7-1200 PLCs
- TIA Portal
- Structured PLC programming
- SCL / Structured Text, LAD and/or FBD
- Process sequencing and state machines
- Recipe-driven automation
- Analog signal processing and scaling
- Process parameter ramping
- Industrial RS485 communication
- Modbus RTU
- Industrial fault handling and interlocks
- Development of structured and maintainable PLC software

Experience with any of the following would be an advantage:

- Scientific equipment
- Laboratory automation
- Vacuum systems
- Gas handling systems
- Thermal/process equipment
- Plasma or high-power systems
- Semiconductor or advanced materials equipment
- Special-purpose industrial machinery To Apply

Please provide

1. Your experience with Siemens S7-1200 and TIA Portal
2. Examples of relevant PLC or process automation projects
3. Your experience with state machine and sequence programming
4. Your experience developing reusable PLC function blocks
5. Your experience with analog process control and parameter ramping
6. Your experience with RS485 / Modbus RTU & TCP IP
7. Confirmation of your availability for in office engineering and commissioning
8. Confirmation that you are willing to sign an NDA before receiving detailed project information

📌 Senior Freelance Siemens-1200 PLC Automation Engineer (Goregaon)
🏢 Stanzekiel Software (P
📍 Goregaon