Python串行端口读取，直到完成

然后发送“I”，后跟N和C，然后从文本文件中发送9个十六进制数字。下面的代码读了一行，进入了编写部分，阅读了整个文本文件

#!/usr/bin/python

I am struggling with quite the simple problem. I want to read some data from the serial port first than start writing the data. The data reading and writing works well. The problem is I need to read first around 7 lines like 

X7_SEM_V3_6
ICAP OK
SA OK
IC OK
RBDK OK
status OK
S OK

对所有七行执行此操作后，读取并发送I。我希望它在发送I之前读取所有七行并开始工作。这是while循环。如果我用别的东西，它只会读第一行，然后卡住。请找个人帮忙

X7_SEM_V3_6
000062240
000062241
ICAP
000062240
000062241
so on

import serial, time
import binascii
ser = serial.Serial()
ser.port = "/dev/ttyUSB1"
ser.baudrate = 38400
ser.bytesize = serial.EIGHTBITS 
ser.parity = serial.PARITY_NONE 
ser.stopbits = serial.STOPBITS_ONE              
ser.xonxoff = False    
ser.rtscts = False    
ser.dsrdtr = False  
number_address = 1341602
number_char = 9  
timeout=1
f=open('lut.txt','r')

try: 
    ser.open()
except Exception, e:
    print "error open serial port: " + str(e)
    exit()

if ser.isOpen():

    try:
         ser.flushInput()
         ser.flushOutput()
# reading        
         max_packet = 20
         lines = 0

         while True:
            byteData = ser.read_until('\r',max_packet)
            newdata=str(byteData)
            print newdata.strip()

        #ser.write('I')

            ser.write('I')
            time.sleep(0.01)
            for line in f.readlines():
              print line
              ser.write('N')
              time.sleep(0.01)
              ser.write(' ')
              time.sleep(0.01)
              ser.write('C')
              time.sleep(0.01)
              for i in line:
                newdata=i
                ser.write(newdata)
                time.sleep(0.01)

    except Exception, e1:
        print "error communicating...: " + str(e1)

else:
    print "cannot open serial port "