我需要通过串口读取由Arduino发送的一些数字，然后将这些数字插入到MySQL表中。

这是我的密码：

import mysql.connector, serial
ser = serial.Serial(port='/dev/ttyACM3', baudrate='9600')
ser.isOpen()
read_port = ser.readline()
print (read_port)
mysql_connection = mysql.connector.connect(host="localhost", user="optim_admin", passwd="marcopolo", database="optimbit_acces")
cursor = mysql_connection.cursor()
sql1 = "insert into check_in (card, checkin) values (%s, Now()); ", (read_port)
cursor.execute(sql1)
mysql_connection.close()

这是我的错误：

 Traceback (most recent call last):
  File "/home/admin1/Documents/OptimAcces/db_service_connect.py", line 10, in <module>
    cursor.execute(sql1, (str(read_port.decode('unicode_escape').encode('ascii', 'utf-8')), ))
  File "/usr/local/lib/python2.7/dist-packages/mysql/connector/cursor.py", line 492, in execute
    stmt = operation.encode(self._connection.python_charset)
AttributeError: 'tuple' object has no attribute 'encode'
Process finished with exit code 1

如何纠正此错误？