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comparison example.py @ 5:51d1fc44a753

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Add variable timeout for reads. Modify the example to use it & print how long curve takes.
author Daniel O'Connor <darius@dons.net.au>
date Wed, 13 May 2009 17:17:01 +0930
parents 62ffab79227e
children 813e183cfd49
comparison
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4:6b360c30eed6 5:51d1fc44a753
8 def main(): 8 def main():
9 u = usb488.USB488Device() 9 u = usb488.USB488Device()
10 print "Found device" 10 print "Found device"
11 11
12 u.write("*IDN?") 12 u.write("*IDN?")
13 print "ID is..", 13 print "IDN reports " + u.read()
14 print u.read()
15 14
16 u.write("DATA:ENC RIB") # Big endian signed 15 u.write("DATA:ENC RIB") # Big endian signed
17 u.write("DATA:WIDTH 2") # 2 bytes wide 16 u.write("DATA:WIDTH 2") # 2 bytes wide
18 u.write("SELECT:CH1 ON") # Turn channel 1 on 17 u.write("SELECT:CH1 ON") # Turn channel 1 on
19 u.write("DATA:SOURCE CH1") # Set the curve source to channel 1 18 u.write("DATA:SOURCE CH1") # Set the curve source to channel 1
20 u.write("CURVE?") # Ask for the curve data 19 u.write("CURVE?") # Ask for the curve data
21 time.sleep(1) # Wait for the data.. 20 then = time.time()
22 # XXX: need some way of polling 21 result = u.read(1.0) # Takes the CRO a while for this
23 result = u.read() 22 now = time.time()
23 print "CURVE read took %f milliseconds" % ((now - then) * 1000.0)
24 data = result[13:] # Chop off the header 24 data = result[13:] # Chop off the header
25 dattype = numpy.dtype('>h') # Big endian 16 bit quantity 25 dattype = numpy.dtype('>h') # Big endian 16 bit quantity
26 ary = numpy.fromstring(data, dtype = dattype) 26 ary = numpy.fromstring(data, dtype = dattype)
27 pylab.plot(ary) 27 pylab.plot(ary)
28 pylab.show() 28 pylab.show()