Communicating over serial to a stepper motor

edit

Hi,

I want to make a simple node to subscribe to a topic and publish/write these to a serial port. I have managed to send what i want and get the response i need but i can't implement this in a ROS node script. All the rosserial guides i have read is about arduino. However i only want to read and write to this port. Not edit whats on the other side of the ports software.

So basically i have a python script that send commands which gives me the wanted response. (Positioning of a stepper motor of type Nanotec PD2-n) But how can i implement this into a node?

Appreciate help in python and ROS (new to both)

import serial, fcntl, struc, time

#establish connection with serial port

ser = serial.Serial(
port='/dev/ttyUSB0',
baudrate=115200,
timeout=1,
parity=serial.PARITY_NONE,
stopbits=serial.STOPBITS_ONE,
bytesize=serial.EIGHTBITS
)

# commands as following: "absolute mode" , "move to position 'angle' " , "execute"

commands = ['#1p2\r',
'#1s' + str(angle) + '\r',
'#1A\r',
]

if ser.isOpen():
    ser.flushOutput()
    ser.flushInput()
    for data in commands
        ser.write(data)
        response = ser.readline()
        print("read data: " + response)
ser.Close()
else:
    print "cannot open serial port"