The developers have created a 4-port Modbus TCP gateway based on the NAPI-C industrial computer (Rockchip RK3308) and the FT4232H chip. The device features four independent RS-485 lines, each mapped to a separate TCP port, managed by a single configuration and service.
The software solution, mbusgw-t2r, is open-source under the Apache 2.0 license. Unlike standard solutions like mbusd, which require separate instances for each port, this gateway handles multiple lines within a single process. The hardware includes an integrated watchdog to ensure automatic recovery after system failures.
Performance testing demonstrated stable operation with 59 requests per second on each of the four lines at 19200 baud. During a long-term stress test involving nearly 400,000 requests, the system recorded zero errors, with no memory or thread leaks detected.
The developers addressed specific technical challenges, such as the default FTDI driver latency, which caused CRC errors by splitting data packets. This was resolved via udev settings. The NAPI-C module is registered in the Russian Ministry of Industry and Trade registry, classifying the gateway as a product of Russian origin.
