runoff_calibration.py

import usb.core, time, sys

#find trainer model for Windows and Linux
product=0

idpl = [0x1932, 0x1942]#iflow, fortius
for idp in idpl:
  dev = usb.core.find(idVendor=0x3561, idProduct=idp) #find iflow device
  if dev != None:
    product=idp
    break

if product == 0:
  print "Trainer not found"
  sys.exit()
  
dev.set_configuration() #set active configuration
  
#initialise TACX USB device
byte_ints = [2,0,0,0] # will not read cadence until initialisation byte is sent
byte_str = "".join(chr(n) for n in byte_ints)
dev.write(0x02,byte_str)



print "CALIBRATION TIPS: Tyre pressure 100psi (unloaded and cold), aim for 7.2s rolloff"
print "Warm up for 2 mins, then cycle 30kph-40kph for 30s then to above 40kph then stop pedalling and freewheel"
print "Rolldown timer will start automatically when you hit 40kph, so stop pedalling quickly!"

speed = 0
running = True
rolldown = False
rolldown_time = 0
try:
  while running == True:
    time.sleep(0.1)
    #get data
    if product==0x1932:#if is an iflow
      data = dev.read(0x82,64) #get data from device
      #get values reported by trainer
      fs = int(data[33])<<8 | int(data[32])
      speed = round(fs/2.8054/100,1)#speed kph
      cadence = int(data[44])
      if len(data) > 40:
        pedecho = data[42]
      else:
        pedecho = 0
      time.sleep(0.1)
      #send data
      #2700 res=6
      r6=int(2700)>>8 & 0xff #byte6
      r5=int(2700) & 0xff #byte 5
      byte_ints = [0x01, 0x08, 0x01, 0x00, r5, r6, pedecho, 0x00 ,0x02, 0x52, 0x10, 0x04]
      byte_str = "".join(chr(n) for n in byte_ints)
      dev.write(0x02,byte_str)#send data to device
    if speed > 40 or rolldown == True:
      if rolldown_time == 0:
        rolldown_time = time.time()#set initial rolldown time
      sys.stdout.write("Rolldown timer started - STOP PEDALLING! %s \r" % ( round((time.time() - rolldown_time),1) ) )
      sys.stdout.flush()
      rolldown = True
      if speed < 0.1:#wheel stopped
        running = False#break loop
        print("Rolldown time = %s seconds                  " % (round((time.time() - rolldown_time),1)))
    else:
      sys.stdout.write("Speed: %s Cadence: %s  \r" % (str(speed).zfill(4),str(cadence)) )
      sys.stdout.flush()

  if time.time() - rolldown_time > 7.5 : 
    print "More pressure from trainer on tyre required"
  elif time.time() - rolldown_time < 6.5 : 
    print "Less pressure from trainer on tyre required"
  else:
    print "Calibration OK - good to train and get reasonable power numbers!"
  raw_input("Press Enter to continue...")
except KeyboardInterrupt:
  pass