from fastapi import FastAPI
from pymodbus.client import ModbusSerialClient
import time
import threading
from queue import Queue

serial_port = "COM4"  
baud_rate = 9600
modbus_client = ModbusSerialClient(method='rtu', port=serial_port, baudrate=baud_rate)

modbus_queue = Queue()

def poll_modbus():
    while True:
        if modbus_client.connect():
            response = modbus_client.read_holding_registers(address=0, count=1, unit=1)
            if not response.isError():
                modbus_queue.put(response.registers[0])
            modbus_client.close()
        time.sleep(1)  

threading.Thread(target=poll_modbus, daemon=True).start()

app = FastAPI()

@app.get("/modbus_data")
async def get_modbus_data():
    if not modbus_queue.empty():
        modbus_value = modbus_queue.get()  
        return {"modbus_data": modbus_value}
    else:
        return {"error": "No data received"}

@app.get("/")
async def root():
    return {"message": "Welcome to Modbus with FastAPI"}


if __name__ == "__main__":
    import uvicorn
    uvicorn.run(app, host="0.0.0.0", port=12345)