Inhaltsverzeichnis
Siglent SDM3065x Bench Multimeter
SCPI and Fast Sampling
This bench multimeter needs a very special procedure, to get the advantage of fast measurements.
This article should be applicable with minor adjustments for the all the new Siglent DMM's: SDM3045X, SDM3055, SDM3055A, SDM3065X
Problem
The default command Measure:Voltage:DC? takes about 2s. What next came to mind, was the command Read?. It answers very fast, but is delivers measurements from the past - could be some minutes or even hours old. Even clearing the buffer with R? doesn't change that situation.
Another Problem is, that when the DMM got it's first Measure command, the display will not update any more, also mentioned by a user in the EEVblog Forum, see Links [2].
Solution
For both problems I gladly found the solution. The approach is like this:
- set the sampling counter to MAX (600 Mio)
- clear the buffer with
R?(to avoid getting an old value on the first reading) - set trigger source to 'BUS'
- initiate the DMM (arms the trigger)
- trigger it by sending
*TRG - read samples with
R? 1
When the DMM isn't asked for any value, it will sample with the preset NPLC setting (200ms by default) and therefore also updates the LCD reading.
If we want the latest value from the memory, we query for it with R? 1.
Wrong User Manual
Due to false documentation in the Siglent SDM3065X Remote Manual, Version RC06036-E01A, 2017 it was a hard way to find that solution.
Python Code
Below you can find a python class for communicating with it. It implements the upper approach.
A typical usage could be:
import siglent_sdm3065x dmm = siglent_sdm3065x.SDM3065X('10.0.0.114') dmm.reset() # setup: v = dmm.getVoltageDC('20V',0.05) # set NPLC to 0.05 which is 1ms in a 50Hz grid print(v) # further readings: for i in range(10): print(dmm.read())
- siglent_sdm3065x.py
# Python3 Class for controlling a Siglent SDM3065x Bench Multimeter via Ethernet and SCPI # MIT License # Copyright 2018 Karl Zeilhofer, Team14.at # 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. import decimal import socket import sys import time _timeoutCmd = 10 # seconds _timeoutQuery = 10 # seconds class SDM3065X: def __init__(self, ip): self.ipAddress = ip self._port = 5024 # TCP port, specific to these devices, the standard would be 5025 self.NPLC = ['100','10','1','0.5','0.05','0.005'] # available Integration durations in number of powerline cycles # set with Voltage:DC:NPLC or similar self.voltageRangeDC = ['200mV','2V','20V','200V','1000V','AUTO'] # set with VOLTage:DC:RANGe self.voltageRangeAC = ['200mV','2V','20V','200V','750V','AUTO'] # set with VOLTage:AC:RANGe self.currentRangeDC = ['200uA','2mA','20mA','200mA','2A','10A','AUTO'] # set with CURRent:DC:RANGe self.currentRangeAC = ['200uA','2mA','20mA','200mA','2A','10A','AUTO'] # set with CURRent:AC:RANGe self._PrintDebug = True def _abort(self, msg): # TODO 2: something like this: traceback.print_stack(sys.stdout) print('Abort for device IP=' + self.ipAddress + ':' + str(self._port)) print(msg) print('ERROR') sys.exit(-1) def _debug(self, msg): if(self._PrintDebug): print(self.ipAddress + ':' + str(self._port) + ': ' + msg) def reset(self): self._runScpiCmd('*RST') def getVoltageDC(self, range='AUTO', integrationNPLC='10'): self._runScpiCmd('abort') # stop active measurement self._runScpiCmd('Sense:Function "Voltage:DC"') if str(integrationNPLC) not in self.NPLC: self._abort('invalid integrationNPLC: ' + str(integrationNPLC) + ', use ' + str(self.NPLC)) self._runScpiCmd('Sense:Voltage:DC:NPLC ' + str(integrationNPLC)) if range not in self.voltageRangeDC: self._abort('invalid range: ' + range + ', use ' + str(self.voltageRangeDC)) self._runScpiCmd('Sense:Voltage:DC:Range ' + range) if range == 'AUTO': self._runScpiCmd('Sense:Voltage:DC:Range:AUTO ON') else: self._runScpiCmd('Sense:Voltage:DC:Range:AUTO OFF') self._runScpiCmd('Trigger:Source Bus') self._runScpiCmd('Sample:Count MAX') # continiuous sampling, max. 600 Mio points self._runScpiCmd('R?') # clear buffer self._runScpiCmd('Initiate') # arm the trigger self._runScpiCmd('*TRG') # send trigger (samples exact one value) return self.read() def getCurrentDC(self, range='AUTO', integrationNPLC='10'): self._runScpiCmd('abort') # stop active measurement self._runScpiCmd('Sense:Function "Current:DC"') if str(integrationNPLC) not in self.NPLC: self._abort('invalid integrationNPLC: ' + str(integrationNPLC) + ', use ' + str(self.NPLC)) self._runScpiCmd('Sense:Current:DC:NPLC ' + str(integrationNPLC)) if range not in self.currentRangeDC: self._abort('invalid range: ' + range + ', use ' + str(self.currentRangeDC)) self._runScpiCmd('Sense:Current:DC:Range ' + range) if range == 'AUTO': self._runScpiCmd('Sense:Current:DC:Range:AUTO ON') else: self._runScpiCmd('Sense:Current:DC:Range:AUTO OFF') self._runScpiCmd('Trigger:Source Bus') self._runScpiCmd('Sample:Count MAX') # continiuous sampling, max. 600 Mio points self._runScpiCmd('R?') # clear buffer self._runScpiCmd('Initiate') # arm the trigger self._runScpiCmd('*TRG') # send trigger (samples exact one value) return self.read() # read() # get latest value, with current settings # saves a lot of time! # the DMM aquires in the meanwhile, and read fetches the most recent value # getVoltageDC() or getCurrentDC() must be called before! # typical session with netcat: # >>r? 1 # #215+1.36239593E+00 # ^ 2 = number of digits with describe the packet length def read(self): ans = '>>' t0 = time.time() while ans == '>>': if (time.time()-t0)>5: self._abort('timeout in read(), forgot to start the measurement?') ans = self._runScpiQuery('R? 1') # get latest data if ans == '>>': time.sleep(0.1) ans = str(ans) nDigits = int(ans[1]) ans = ans[(2+nDigits):] return self.str2engNumber(ans) def _runScpiCmd(self, cmd, timeout=_timeoutCmd): self._debug('_runScpiCmd(' + cmd + ')') BUFFER_SIZE = 1024 s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) s.settimeout(timeout) data = "" try: s.connect((self.ipAddress, self._port)) data = s.recv(BUFFER_SIZE) # discard welcome message s.send(bytes(cmd + '\n', 'utf-8')) data = s.recv(BUFFER_SIZE) except socket.timeout: self._abort('timeout on ' + cmd) s.close() retStr = data.decode() self._debug('>>' + retStr) return retStr def _runScpiQuery(self, query, timeout=_timeoutQuery): self._debug('_runScpiQuery(' + query + ')') BUFFER_SIZE = 1024 s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) s.settimeout(timeout) data = b"" try: s.connect((self.ipAddress, self._port)) data = s.recv(BUFFER_SIZE) # discard welcome message s.send(bytes(query + '\n', 'utf-8')) data = s.recv(BUFFER_SIZE) except socket.timeout: self._abort('timeout on ' + query) s.close() retStr = data.decode() retStr = retStr.strip('\r\n') return retStr def str2engNumber(self, str): x = decimal.Decimal(str) return x.normalize().to_eng_string()