python - Jumbled out put of RFID Tags -

i working on project, in have interface multiple rfid readers (i'm using em 18, serial out) raspberry pi. i'm using usb ttl converter connect em 18 raspberry pi. i've connected 2 rfid readers using usb ttl adapter. code 1 station

code

import serial, time while true:     try:         print 'station 1 ready!! please show card'                 card_dataa = serial.serial('/dev/ttyusb0', 9600).read(12)         print card_dataa         continue     except serial.serialexception:         print 'station 1 down'     break 

my issues are

1. i readings both rfid readers in same program simultaneously.

2. i've 2 programs above code, station1.py , station2.py.

station1.py usb0 , station2.py usb1. executing programs in different terminal simultaneously.

for example station1.py in terminal 1 , station2.py in terminal 2. program executes fine, readings jumbled. example, 6e0009d2cc79 , 4e0070792760 tag id's i'm using testing. if i'm executing 1 program i'm getting reading properly, if i'm executing both programs simultaneously in 2 terminals i'm getting tag id's jumbled.

3. i want combine both readings in same program.

thanks in advance

i'd recommend create new serial object once , reading multiple times, needed:

import serial, time  try:     station1 = serial.serial('/dev/ttyusb0', 9600)     print 'station 1 ready!! please show card' except serial.serialexception:         print 'station 1 down'  while true:     card_dataa = station1.read(12)     print card_dataa 

optionally can set timeout of 0:

import serial, time  try:     station1 = serial.serial('/dev/ttyusb0', 9600,timeout=0)     print 'station 1 ready!! please show card' except serial.serialexception:         print 'station 1 down'  while true:     card_dataa = station1.read(12)     if len(card_dataa) > 0: print card_dataa 

you should able open 2 serial connections in same program:

import serial, time  station1 = none station2 = none  try:     station1 = serial.serial('/dev/ttyusb0', 9600,timeout=0)     print 'station 1 ready!! please show card' except exception,e:         print 'station 1 down',e  try:     station2 = serial.serial('/dev/ttyusb1', 9600,timeout=0)     print 'station 2 ready!! please show card' except exception,e:         print 'station 2 down',e   while true:     if station1 != none:         card_dataa1 = station1.read(12)         if len(card_dataa1) > 0:    print card_dataa1     if station2 != none:         card_dataa2 = station2.read(12)         if len(card_dataa2) > 0:    print card_dataa2 

this means 2nd reader wait 1st reader finish before printing, why fingaz recommended threading.

here's basic commented proof of concept threading:

import threading,time,serial  #subclass threading.thread class rfidserialthread(threading.thread):     sleep_time = 0.001 #setup sleep time (update speed)     #constructor 3 parameters: serial port, baud , label reader it's easy spot     def __init__(self,port,baud,name):          threading.thread.__init__(self) #initialize instance thread         self.isalive = false #keep track if thread needs run(is setup , able go) or not         self.name = name     #potentially handy debugging         self.data = ""       #a placeholder data read via serial         self.station = none  #the serial object property/variable         try:             self.station = serial.serial(port,baud,timeout=0) #attempt initialize serial             self.isalive = true #and flag thread running         except exception,e:              print name + " down",e #in case of errors print message, including station/serial port      def run(self): #this gets executed when thread started         while self.isalive:             if self.station != none:    self.data = self.station.read(12) #read serial data             time.sleep(rfidserialthread.sleep_time)  if __name__ == '__main__':     #initialize 2 readers     station1 = rfidserialthread('/dev/ttyusb0',9600,"station #1")     station2 = rfidserialthread('/dev/ttyusb1',9600,"station #2")     #start threads     station1.start()     station2.start()      while true:#continously print data (if any)         if len(station1.data) > 0:  print station1.name,station1.data         if len(station2.data) > 0:  print station2.name,station2.data 

note haven't attached actual hardware test, may not work is, should provide enough info progress.

i suggest trying physically distance readers. depending on readers , capabilities may interfering witch each other might result in faulty data. in case still have issues jumbled data, i'd try figure out problem taking assumptions out.(e.g. issue hardware (readers interfering, broken reader, loose usb connector, etc.) or software(serial port not initialized/flushed/etc.), taking 1 thing out @ time)