IEC61850-Modbus Python Gateway

I am building a small Windows 10 service that will sit between an IEC 61850 IED and downstream Modbus-TCP clients. The gateway must act as an MMS client, pull a defined set of Logical Nodes (both status and analog), then expose each value as a Holding Register on a Modbus-TCP server that can listen on any user-selectable port.

Key details you should know
• The Windows PC runs Python 3.9.
• The IED is reachable over a direct Ethernet connection—no serial converters or intermediate devices.
• All data mapping must come from the device’s ICD/SCL file, so parsing that file correctly is critical.
• The program has to auto-start with the OS and run continuously (24/7) without manual intervention.

I expect you to lean on libiec61850 for the MMS side and something like pymodbus (or equivalent) for the server side, but I am open to alternatives if you can justify stability and license compatibility. Experience with industrial protocols and non-stop services is a plus.

Deliverables
• Full, well-commented Python source code
• A YAML/JSON mapping file generated from the ICD/SCL that clearly links each data point to its Modbus register address
• Step-by-step installation & auto-start guide for Windows 10 (task scheduler, NSSM, or your preferred approach)
• Remote test support so we can confirm live read/write behaviour against my IED

Acceptance will be based on:
1. Successful polling of at least ten designated data points from the IED.
2. Accurate, real-time reflection of those values on the Modbus-TCP server.
3. Service stability during a 24-hour soak test.

If this sounds like a fit, let’s discuss your proposed design and timeline.