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Add ability to partially grab memory #13

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Add ability to partially grab memory #13

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d7df64b
allow partial grab of internal buffer
EtherDeltaRep-2 Oct 21, 2018
e27c36a
clean up debug print
EtherDeltaRep-2 Oct 21, 2018
1e0411e
off-by-one fix
EtherDeltaRep-2 Oct 21, 2018
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24 changes: 16 additions & 8 deletions ds1054z/__init__.py
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Original file line number Diff line number Diff line change
Expand Up @@ -178,7 +178,7 @@ def waveform_preamble_dict(self):
keys = 'fmt, typ, pnts, cnt, xinc, xorig, xref, yinc, yorig, yref'.split(', ')
return dict(zip(keys, self.waveform_preamble))

def get_waveform_samples(self, channel, mode='NORMal'):
def get_waveform_samples(self, channel, mode='NORMal', start=1, end=None):
"""
Returns the waveform voltage samples of the specified channel.

Expand All @@ -204,7 +204,7 @@ def get_waveform_samples(self, channel, mode='NORMal'):
:rtype: list of float values
"""

buff = self.get_waveform_bytes(channel, mode=mode)
buff = self.get_waveform_bytes(channel, mode=mode, start=start, end=end)
fmt, typ, pnts, cnt, xinc, xorig, xref, yinc, yorig, yref = self.waveform_preamble
samples = list(struct.unpack(str(len(buff))+'B', buff))
samples = [(val - yorig - yref)*yinc for val in samples]
Expand All @@ -217,7 +217,7 @@ def get_waveform_samples(self, channel, mode='NORMal'):
samples = samples[:-num] + [float('nan')] * num
return samples

def get_waveform_bytes(self, channel, mode='NORMal'):
def get_waveform_bytes(self, channel, mode='NORMal', start=1, end=None):
"""
Get the waveform data for a specific channel as :py:obj:`bytes`.
(In most cases you would want to use the higher level
Expand Down Expand Up @@ -247,7 +247,7 @@ def get_waveform_bytes(self, channel, mode='NORMal'):
if mode.upper().startswith('NORM') or (self.running and mode.upper().startswith('MAX')):
return self._get_waveform_bytes_screen(channel, mode=mode)
else:
return self._get_waveform_bytes_internal(channel, mode=mode)
return self._get_waveform_bytes_internal(channel, mode=mode, start=start, end=end)

def _get_waveform_bytes_screen(self, channel, mode='NORMal'):
"""
Expand Down Expand Up @@ -297,7 +297,7 @@ def _get_waveform_bytes_screen(self, channel, mode='NORMal'):
self.mask_begin_num = None
return buff

def _get_waveform_bytes_internal(self, channel, mode='RAW'):
def _get_waveform_bytes_internal(self, channel, mode='RAW', start = 1, end = None):
"""
This function returns the waveform bytes from the scope if you desire
to read the bytes corresponding to the internal (deep) memory.
Expand All @@ -310,15 +310,23 @@ def _get_waveform_bytes_internal(self, channel, mode='RAW'):
self.write(":WAVeform:FORMat BYTE")
self.write(":WAVeform:MODE " + mode)
wp = self.waveform_preamble_dict
pnts = wp['pnts']
if end is None:
pnts = wp['pnts'] - start - 1# to account for len(buff) < pnts later
else:
pnts = min(wp['pnts'],end - start)
buff = b""
max_byte_len = 250000
pos = 1
pos = start
# print "POINTS IS %d" % pnts
while len(buff) < pnts:
# print "LEN(BUFF) is %d" % len(buff)
self.write(":WAVeform:STARt {0}".format(pos))
end_pos = min(pnts, pos+max_byte_len-1)
print ":WAVeform:STARt {0}".format(pos)
end_pos = min(pos + pnts, pos+max_byte_len-1)
self.write(":WAVeform:STOP {0}".format(end_pos))
print ":WAVeform:STOP {0}".format(end_pos)
tmp_buff = self.query_raw(":WAVeform:DATA?")
# print len(tmp_buff)
buff += DS1054Z.decode_ieee_block(tmp_buff)
pos += max_byte_len
return buff
Expand Down