import minimalmodbus

mb_address = 1

modbus_read = minimalmodbus.Instrument('/dev/ttyUSB0',mb_address)

modbus_read.serial.baudrate = 38400

modbus_read.serial.bytesize = 8

modbus_read.serial.parity = minimalmodbus.serial.PARITY_NONE

modbus_read.serial.stopbits = 1

modbus_read.serial.timeout = 0.5

modbus_read.mode = minimalmodbus.MODE_RTU

modbus_read.clear_buffers_before_each_transaction = True

modbus_read.close_port_after_each_call = True

print("")

print("Requesting Data ...")

# NOTE-- Register addresses are offset from 40001 so inputting register 0 in the code is actually 40001, 3 = 40004 etc...

# Arguments - (register start address, number of registers to read, function code)

data =modbus_read.read_registers(148, 1, 3)

print("")

print("The totalcurrent is",data)

modbus_read.serial.close()

THE ERROR IS: