Hello everyone,
I am having a problem receiving events from some com objects I am working
with. win32com has performed beautifully so far and the code can call methods
and manipulate properties with no problems. However I cannot seem to figure out
why I am not receiving events. It is probably just a lack of knowledge on my
part about com but thats why I am asking.
The com object that this code accesses follows a specification for talking
to point of sale devices called OPOS. In particular it is a control for a
magnetic stripe reader device. I need to receive the DataEvent event from the
control. I am using the method prototypes from the makepy utility for the event
class but I never see their print statements executed on my output.
The DataEvent is being fired though the various card properties are not
filled in until the event is generated and those show up every time. Also I
have used the ActiveX test shell from vc++ 6 and it receives the events. In the
output I have scrubbed the card number and name (its actually a fake test card
but it seems safer this way) but the data is there and correct. Thank you for
your help in advance.
-Seth Sims
-----------event.py-------------
import win32com.client as client
import pythoncom
class OPOSEventSink:
def OnDirectIOEvent(self, EventNumber, pData, pString):
"""method DirectIOEvent"""
print "direct io"
def OnDataEvent(self, Status):
"""method DataEvent"""
print "data"
def OnStatusUpdateEvent(self, Data):
"""method StatusUpdateEvent"""
print "status update"
def OnErrorEvent(self, ResultCode, ResultCodeExtended, ErrorLocus,
pErrorResponse):
"""method ErrorEvent"""
print "error"
if __name__ == '__main__':
msr = client.DispatchWithEvents("OPOS.MSR", OPOSEventSink)
#Ready the device
msr.Open("Ing6XXX")
msr.ClaimDevice(-1)
#setup the magnetic stripe reader
#tell the device to turn its self off when a swipe is read
msr.AutoDisable = True
msr.DataEventEnabled = True
#read all 4 tracks
msr.TracksToRead = 0xf
#hold events till I tell you to send them
msr.FreezeEvents = True
#turn the device on
msr.DeviceEnabled = True
print "please swipe a card"
#when this loop finishes there has
#been a successful swipe of a card
#and a data event is waiting to be
#released in the com object
while msr.DataCount < 1:
pass
#by the OPOS specification these
#attributes are set as blank strings
#until a data event is fired
print 'before unfreezing events should be blank'
print 'Account number:', msr.AccountNumber, \
'\nName:', msr.Surname, '\n'
#release the events
msr.FreezeEvents = False
print 'events thawed should still be blank'
print 'Account number:', msr.AccountNumber, \
'\nName:', msr.Surname, '\n'
pythoncom.PumpWaitingMessages()
print 'after pump waiting messages now the values should be there'
print 'Account number:', msr.AccountNumber, \
'\nName:', msr.Surname, '\n'
msr.ReleaseDevice()
msr.Close()
---------- Output -------------
please swipe a card
before unfreezing events should be blank
Account number:
Name:
events thawed should still be blank
Account number:
Name:
after pump waiting messages now the values should be there
Account number: <scrubed by me>
Name: <ditto>
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