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Re: [Linux-gpib-general] RSQ example help
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From: Wilhelm K. <ku...@t-...> - 2021-12-21 20:00:26
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Hello Lucas,
I'm using linux-gpib with python 3 on my laptop with Ubuntu 20.04. I
have also the DMM Keithley Model 2000. Because this device is able to
understand SCPI I used the following code to read out the stored data:
def read_buffer(geraetename, var):
Werte = []
Board = gpib.find("USB-GPIB") # find interface
address in gpib.config and assign it to Board
Name = gpib.find(geraetename) # find device address
in gpib.config and assign it to Name
gpib.timeout(Name,0) # set Timeout
to 'never timeout'
gpib.write(Name,":DATA:DATA?") # ask for data
String = gpib.read(Name,var*16) # read data and
assign it to String
gpib.wait(Board, 0x100) # wait until
I/O-Operation complete
i=1
while i<=var:
Werte.append(float(String[(i-1)*16:(i-1)*16+15]))
i=i+1
return Werte
With the functions:
def clear_buffer(geraetename):
Name = gpib.find(geraetename)
gpib.write(Name,":DATA:CLEAR")
def set_buffer_size(geraetename, var):
Name = gpib.find(geraetename)
cmd = ""
if var>1:
if var<1025:
cmd=":DATA:POINTS "+str(var)
gpib.write(Name,cmd)
you can clear and set the buffer.
But I have to say, that these were my first tries to program the
Keithley Model 2000. It works but it is not a very good programming
technique. I searched for better solutions and found the python-ivi
project from Alex Forencich. For me it's the best approach to use
measurement equipment with python (see
https://alexforencich.com/wiki/en/python-ivi/start). I started to write
a python-ivi driver for the Keithley Model 2000. It is like this:
"""
Python Interchangeable Virtual Instrument Library
Copyright (c) 2012-2014 Alex Forencich, 2021 Wilhelm Kusian
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to
deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
"""
from .. import ivi
from .. import dmm
from .. import scpi
# for Keithley 2000 individualized Tupel
MeasurementAverageMapping = {
'dc_volts': 'volt:dc:average:state',
'ac_volts': 'volt:ac:average:state',
'dc_current': 'curr:dc:average:state',
'ac_current': 'curr:ac:average:state',
'two_wire_resistance': 'res:average:state',
'four_wire_resistance': 'fres:average:state'}
MeasurementConfigureMapping = {
'dc_volts': 'configure:volt:dc',
'ac_volts': 'configure:volt:ac',
'dc_current': 'configure:curr:dc',
'ac_current': 'configure:curr:ac',
'two_wire_resistance': 'configure:res',
'four_wire_resistance': 'configure:fres'}
MeasurementIntTimeMapping = {
'dc_volts': 'volt:dc:nplcycles',
'ac_volts': 'volt:ac:nplcycles',
'dc_current': 'curr:dc:nplcycles',
'ac_current': 'curr:ac:nplcycles',
'two_wire_resistance': 'res:nplcycles',
'four_wire_resistance': 'fres:nplcycles'}
MeasurementRangeMapping = {
'dc_volts': 'volt:dc:range',
'ac_volts': 'volt:ac:range',
'dc_current': 'curr:dc:range',
'ac_current': 'curr:ac:range',
'two_wire_resistance': 'res:range',
'four_wire_resistance': 'fres:range'}
TriggerSourceMapping = {
'bus': 'bus',
'external': 'ext',
'immediate': 'imm',
'timer': 'tim',
'manual': 'man'}
class keithley2000(scpi.dmm.Base, scpi.dmm.MultiPoint,
scpi.dmm.SoftwareTrigger):
"Keithley 2000 IVI DMM driver"
def __init__(self, *args, **kwargs):
self.__dict__.setdefault('_instrument_id', '2000')
super(keithley2000, self).__init__(*args, **kwargs)
self._identity_description = "Keithley 2000 IVI DMM driver"
self._identity_identifier = ""
self._identity_revision = ""
self._identity_vendor = ""
self._identity_instrument_manufacturer = "Keithley"
self._identity_instrument_model = ""
self._identity_instrument_firmware_revision = ""
self._identity_specification_major_version = 1
self._identity_specification_minor_version = 0
self._identity_supported_instrument_models = ['2000']
self._add_property('average', #
additional property to set the filter function
self._get_average,
self._set_average)
self._add_property('int_time', #
additional property to set the integration time
self._get_int_time,
self._set_int_time)
self._add_property('continuous', #
additional property to set the continuous function, i.e. take out of the
idle state
self._get_continuous,
self._set_continuous)
def _initialize(self, resource = None, id_query = False, reset =
False, **keywargs):
"Opens an I/O session to the instrument."
super(keithley2000, self)._initialize(resource, id_query,
reset, **keywargs)
# interface clear
if not self._driver_operation_simulate:
self._clear()
# check ID
if id_query and not self._driver_operation_simulate:
id = self.identity.instrument_model
id_check = self._instrument_id
id_short = id[:len(id_check)]
if id_short != id_check:
raise Exception("Instrument ID mismatch, expecting %s,
got %s", id_check, id_short)
# reset
if reset:
self.utility.reset()
def _get_average(self):
if not self._driver_operation_simulate and not
self._get_cache_valid():
func = self._get_measurement_function()
if func in MeasurementAverageMapping:
cmd = MeasurementAverageMapping[func]
value = int(self._ask("%s?" % (cmd)))
if value == 0:
value = 'off'
elif value == 1:
value = 'on'
self._average = value
self._set_cache_valid()
return self._average
def _set_average(self, value):
if value not in dmm.Auto2:
raise ivi.ValueNotSupportedException()
if not self._driver_operation_simulate:
func = self._get_measurement_function()
if func in MeasurementAverageMapping:
cmd = MeasurementAverageMapping[func]
self._write("%s %d" % (cmd, int(value == 'on')))
self._average = value
self._set_cache_valid()
def _get_int_time(self):
if not self._driver_operation_simulate and not
self._get_cache_valid():
func = self._get_measurement_function()
if func in MeasurementIntTimeMapping:
cmd = MeasurementIntTimeMapping[func]
value = float(self._ask("%s?" % (cmd)))
self._int_time = value*0.02 #
power line cycles back converted to time value in 's'
self._set_cache_valid()
return self._int_time
def _set_int_time(self, value):
if value > 0.2:
value = 0.2
if value < 0.0002:
value = 0.0002
if not self._driver_operation_simulate:
func = self._get_measurement_function()
if func in MeasurementIntTimeMapping:
cmd = MeasurementIntTimeMapping[func]
self._write("%s %g" % (cmd, value/0.02)) # time
value in 's' converted to power line cycles
self._int_time = value
self._set_cache_valid()
def _get_continuous(self):
if not self._driver_operation_simulate and not
self._get_cache_valid():
cmd = ':INITIATE:CONTINUOUS'
value = int(self._ask("%s?" % (cmd)))
if value == 0:
value = 'off'
elif value == 1:
value = 'on'
self._continuous = value
self._set_cache_valid()
return self._continuous
def _set_continuous(self, value):
if value not in dmm.Auto2:
raise ivi.ValueNotSupportedException()
if not self._driver_operation_simulate:
cmd = ':INITIATE:CONTINUOUS'
self._write("%s %d" % (cmd, int(value == 'on')))
self._continuous = value
self._set_cache_valid()
def _get_trigger_source(self): # own
function necessary because Keithley 2000 has more trigger source options
if not self._driver_operation_simulate and not
self._get_cache_valid():
value = self._ask("trigger:source?").lower()
value = [k for k,v in TriggerSourceMapping.items() if
v==value][0]
self._trigger_source = value
self._set_cache_valid()
return self._trigger_source
def _set_trigger_source(self, value):
if value not in TriggerSourceMapping:
raise ivi.ValueNotSupportedException()
if not self._driver_operation_simulate:
self._write(":trigger:source %s" % TriggerSourceMapping[value])
self._trigger_source = value
def _get_range(self): # own
function necessary because no furthe calculation necessary
if not self._driver_operation_simulate and not
self._get_cache_valid():
func = self._get_measurement_function()
if func in MeasurementRangeMapping:
cmd = MeasurementRangeMapping[func]
value = float(self._ask("%s?" % (cmd)))
self._range = value
self._set_cache_valid()
return self._range
def _set_range(self, value):
value = float(value)
if not self._driver_operation_simulate:
func = self._get_measurement_function()
if func in MeasurementRangeMapping:
cmd = MeasurementRangeMapping[func]
self._write("%s %g" % (cmd, value))
self._range = value
self._set_cache_valid()
def _configure(self, max_time): # own
function necessary because configure has an own meaning for this device
if not self._driver_operation_simulate:
func = self._get_measurement_function()
if func in MeasurementConfigureMapping:
cmd = MeasurementConfigureMapping[func]
self._write("%s" % (cmd))
return 0.0
This works fine for me. I'm sure the package of Alex already implemented
to read out the buffer, but I haven't had tested it yet.
Hope this helps you.
Wilhelm
Am 20.12.21 um 21:47 schrieb lucas:
> hello all,
>
> i've successfully installed and tested linux-gpib on a raspberry pi
> 4+b with a NI-GPIB-USB-HS dongle and communicating with a Keithley
> 2000 DMM instrument using python 3. should be fairly common and
> pervasive i have python sending *idn? and receiving the proper
> instrument response, "KEITHLEY INSTRUMENT INC., MODEL 2000, ..." etc.
> so that much is working well.
>
> i'd like to setup the dmm to assert and trigger 25 voltage measurement
> and when complete, signal back to the waiting raspberry that it's
> completed its 25 measurements, and then the computer can download
> those 25 measurements and process the voltages accordingly.
>
> will anyone share or point to some python code where this works
> properly under similar circumstances, linux-gpib, GPIB-USB-HS, python,
> etc.???? especially how to setup the assert, trigger, and raspberry
> wait steps. thank you for your time and effort.
>
> lucas
>
>
>
> _______________________________________________
> Linux-gpib-general mailing list
> Lin...@li...
> https://lists.sourceforge.net/lists/listinfo/linux-gpib-general
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