import pyodbc
server = 'xxxxxxxxDEV'
database = 'SandBox'
username = 'zzzzzzz'
password = 'xxxxxxx'
driver = '{SQL Server}'

cnxn = pyodbc.connect('DRIVER='+driver+';PORT=4853;SERVER='+server+';PORT=4853;DATABASE='+database+';UID='+username+';PWD='+ password)
cursor = cnxn.cursor()
cursor.execute("select * from fieldscreenscheme ")
row = cursor.fetchone()
if row:
    print row

cnxn = pyodbc.connect('DRIVER='+driver+';PORT=43853;SERVER='+server+';PORT=43853;DATABASE='+database+';UID='+username+';PWD='+ password)

pyodbc.Error: ('08001', '[08001] [Microsoft][ODBC SQL Server Driver][DBNETLIB]SQL Server does not exist or access denied. (17) (SQLDriverConnect); [01000] [Microsoft][ODBC SQL Server Driver][DBNETLIB]ConnectionOpen (Connect()). (53); [01S00] [Microsoft][ODBC SQL Server Driver]Invalid connection string attribute (0)')