Elster energy Meter Data Acquisition As1350 model using optical port

I need a small utility that can pull real-time energy consumption values from two specific Elster models—the A1350 and the Ace3500—through my Renesas RTU over a hard-wired link. The meters are already installed and cabled; what I am missing is the software layer (and any low-level protocol work) that will talk to them, parse the live readings, and hand the numbers off in a usable file or stream.

Scope
• Establish reliable wired communication between the RTU and both meters (the Renesas board is available for testing on my bench).
• Read only the live consumption registers; no historical archives or error logs are needed at this stage.
• Output the data in whichever straightforward format you prefer—CSV, JSON, or XML all work for me as long as you document the fields and unit scaling.

Key points to keep in mind
– The polling interval should be configurable so I can throttle traffic if necessary.
– I expect clean, well-commented source code plus a concise setup guide that lets me reproduce your results on a fresh RTU.
– If the meters speak Modbus or any proprietary Elster framing, include your register map or frame structure so future expansion is painless.

Deliverables
1. Source code or script ready to run on the Renesas platform.
2. Connection diagram and configuration notes (baud rate, parity, register addresses, etc.).
3. A short README walking me through compilation, deployment, and a sample pull of live readings.

If you have dealt with Elster protocols or Renesas microcontrollers before, mention it—I value practical experience.