Can I use the USB port of the raspberry pi (model B+) for serial communication (RS232) - python-2.7

Question

I need to interface an old machine (thermostream) to interface with the raspberry pi (model B+)
The thermostream device has a RS232 serial port and I want to connect it to the USB port of the raspberry pi using the RS232 serial to usb cable (where the usb end of the cable is inserted in the pi and the serial end is connected to the device). And I need to write the code in python.
IS this possible? If yes, how should I proceed? Any help is greatly appreciated.

Answer 1

Yes. First you need to install pyserial
Then, in Python, you can use the following function to create a serial object that connects to a port. The usb ports on the pi are dynamically assigned a name and those names can change. This function will enable you to loop through each port for the name. (might not work well with multiple devices attached). Check your connection settings on the device you wish to communicate with (baudrate, parity, stopbits etc) and modify the code to use those settings.
import serial
def serialConnect():
serlocations=['/dev/ttyACM', '/dev/ttyACM0', '/dev/ttyACM1','/dev/ttyACM2', '/dev/ttyACM3','/dev/ttyACM4', '/dev/ttyACM5','/dev/ttyUSB0','/dev/ttyUSB1','/dev/ttyUSB2','/dev/ttyUSB3', '/dev/ttyUSB4', '/dev/ttyUSB5', '/dev/ttyUSB6', '/dev/ttyUSB7', '/dev/ttyUSB8', '/dev/ttyUSB9', '/dev/ttyUSB10','/dev/ttyS0', '/dev/ttyS1', '/dev/ttyS2', 'com2', 'com3', 'com4', 'com5', 'com6', 'com7', 'com8', 'com9', 'com10', 'com11', 'com12', 'com13', 'com14', 'com15', 'com16', 'com17', 'com18', 'com19', 'com20', 'com21', 'com1', 'end']
for device in serlocations:
try:
ser = serial.Serial(
port=device,
baudrate=9600,
parity=serial.PARITY_ODD,
stopbits=serial.STOPBITS_TWO,
bytesize=serial.SEVENBITS
)
print device
return ser
except:
x=0
if device == 'end':
print "No Device Found"
ser = serialConnect()
if ser:
ser.write("TEST")
ser.timeout=5
for i in ser.readlines():
print i