import minimalmodbus

minimalmodbus.BAUDRATE = 9600
minimalmodbus.STOPBITS = 1
address = 123

instrument = minimalmodbus.Instrument('/dev/ttyS0', address) #device, modbus slave address
instrument.debug = True
for _ in range(3):
    try:
        value = instrument.read_float(3873) #register -1 for float
        print("Flow Rate from Flow Meter: {}".format(value))
    except Exception as e:
        print("Error: {}".format(e)) 
    
    try:
        value = instrument.read_float(784) #register -1 for float
        print("Frequency from Drive: {}".format(value))
    except Exception as e:
        print("Error: {}".format(e))