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annotate 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
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62ffab79227e Add example.py with pylab plotting example.
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1 #!/usr/bin/env python
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3 import usb488
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4 import matplotlib.pylab as pylab
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5 import numpy
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6 import time
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7
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8 def main():
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9 u = usb488.USB488Device()
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10 print "Found device"
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12 u.write("*IDN?")
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13 print "IDN reports " + u.read()
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15 u.write("DATA:ENC RIB") # Big endian signed
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16 u.write("DATA:WIDTH 2") # 2 bytes wide
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17 u.write("SELECT:CH1 ON") # Turn channel 1 on
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18 u.write("DATA:SOURCE CH1") # Set the curve source to channel 1
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19 u.write("CURVE?") # Ask for the curve data
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20 then = time.time()
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21 result = u.read(1.0) # Takes the CRO a while for this
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22 now = time.time()
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23 print "CURVE read took %f milliseconds" % ((now - then) * 1000.0)
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24 data = result[13:] # Chop off the header
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25 dattype = numpy.dtype('>h') # Big endian 16 bit quantity
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26 ary = numpy.fromstring(data, dtype = dattype)
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27 pylab.plot(ary)
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28 pylab.show()
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30 if __name__ == "__main__":
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31 main()