def setup_serial(self, port_name=None):
self.usb_send, self.usb_recv, self.usb_err = os.popen3(
self.server_executable_path + (" %d" % -self.device_index),
'b', -1)
self.usb_timestamp = 0
self.__usb_read_leftovers = ''
try:
firstmsg = ''
badloops = 0
while badloops < 5 and (not firstmsg
or not firstmsg[-1] in '\r\n'):
try:
firstmsg += self.usb_err.readline(1000)
except:
traceback.print_exc()
badloops += 1
if badloops == 5:
raise LabProError(
"cannot find or communicate with USB Server: " +
str(self.server_executable_path))
if firstmsg.find("No LabPro Found") >= 0:
raise LabProError(
"USB Server could not connect to a LabPro device at index %d"
% self.device_index)
self.__keep_running = 1
self.status_monitor = threading.Thread(
target=self.read_status, name='USB LabPro status monitor')
self.status_monitor.start()
self.__saved_realtime_fragment = ''
except:
self.__keep_running = 0
self.close()
raise
def read(self, maxlen=None, mode=None):
"read data from USB. If mode is None or 0, strip trailing nulls for ASCII, otherwise leave alone"
self.check_usb_status()
res = ''
db = self.__usb_read_leftovers
while (not maxlen or (maxlen and len(res) < maxlen)):
while len(
db
) < 76: #64 bytes + 8 byte timestamp + 4 byte 0xffffffff flag
try:
db += self.usb_recv.read()
except IOError:
err = sys.exc_info()[1].args
if err[0] in (
11, 29, 35
): #these errors are sometimes returned on a nonblocking empty read
pass #just return empty data
else:
print "USB server disconnected unexpectedly", err
raise LabProError(
"USB server disconnected unexpectedly",
sys.exc_info()[1].args)
if not db:
break #no data at all, just fall out of this inner loop
if not db:
break #doing uncounted read, just take data until it quits coming
flag, tv_sec, tv_usec = struct.unpack('LLL', db[:12])
if flag != 0x00ffffff:
raise LabProError("Bad packet header from LabPro: " +
("%04x %08x %08x" %
(flag, tv_sec, tv_usec)))
self.data_timestamp = float(tv_sec) + float(tv_usec) * 1e-6
res += db[12:76]
db = db[76:]
if not mode:
zp = res.find('\0')
if zp >= 0:
res = res[:zp] #trim any nulls
self.__usb_read_leftovers = db
return res
def setup_serial(self, port_name=None):
self.usb_send, self.usb_recv, self.usb_err = os.popen3(
self.server_executable_path + (" %d" % -self.device_index),
'b', 0)
self.usb_timestamp = 0
self.__usb_read_leftovers = ''
try:
# pipes must be nonblocking
fcntl.fcntl(self.usb_recv, fcntl.F_SETFL, os.O_NONBLOCK)
# pipes must be nonblocking
fcntl.fcntl(self.usb_err, fcntl.F_SETFL, os.O_NONBLOCK)
firstmsg = ''
badloops = 0
while badloops < 5 and not firstmsg:
time.sleep(0.5)
try:
firstmsg = self.usb_err.read()
except:
badloops += 1
if badloops == 5:
raise LabProError(
"cannot find or communicate with USB Server: " +
str(self.server_executable_path))
if firstmsg.find("No LabPro Found") >= 0:
raise LabProError(
"USB Server could not connect to a LabPro device at index %d"
% self.device_index)
self.__keep_running = 1
self.status_monitor = threading.Thread(
target=self.read_status, name='USB LabPro status monitor')
self.status_monitor.start()
self.__saved_realtime_fragment = ''
except:
self.__keep_running = 0
self.close()
raise
def read(self, maxlen=None, mode=None):
"""read data from USB. If mode is None or 0, strip trailing nulls for ASCII, otherwise leave alone."""
self.check_usb_status()
res = ''
db = self.__usb_read_leftovers
while (not maxlen or len(res) < maxlen):
# 64 bytes + 8 byte timestamp + 4 byte 0xffffffff flag
while len(db) < 76:
# a pipe is a seek-and-tallable object, so we can see how much data
# is there this way
self.usb_recv.seek(0, 2)
count = self.usb_recv.tell()
self.usb_recv.seek(0)
if count:
db += self.usb_recv.read(count)
if not db:
break # no data at all, just fall out of this inner loop
if not db:
break # doing uncounted read, just take data until it quits coming
flag, tv_sec, tv_usec = struct.unpack('LLL', db[:12])
if flag != 0x00ffffff:
raise LabProError("Bad packet header from LabPro: " +
("%04x %08x %08x" %
(flag, tv_sec, tv_usec)))
self.data_timestamp = float(tv_sec) + float(tv_usec) * 1e-6
res += db[12:76]
db = db[76:]
if not mode:
zp = res.find('\0')
if zp >= 0:
res = res[:zp] # trim any nulls
self.__usb_read_leftovers = db
return res
def check_usb_status(self):
if not self.__keep_running or not self.status_monitor.isAlive():
raise LabProError("LabPro USB server has died...")
