added to lib: Example Digital Multimeter PT100 readout

7ef2cdaa · Peter Jansweijer · 2ced12d3 · 7ef2cdaa
Commit 7ef2cdaa authored Sep 05, 2017 by Peter Jansweijer
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Keysight_34465A.py sw/lib/Keysight_34465A.py +123 -0

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--- a/sw/lib/Keysight_34465A.py
+++ b/sw/lib/Keysight_34465A.py
+#!/usr/bin/python
+
+"""
+Keysight DMM 34465A remote control
+
+-------------------------------------------------------------------------------
+Copyright (C) 2017 Peter Jansweijer, 'stolen' from Tjeerd Pinkert and freely
+    adjusted
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>
+-------------------------------------------------------------------------------
+
+Usage:
+  Keysight_34465A.py <IP#>
+  Keysight_34465A.py -h | --help
+
+  IP          IP number of the Digital Multimeter
+              (for example: 192.168.32.242 which is its DevNet IP number)
+
+Options:
+  -h --help   Show this screen.
+ 
+"""
+
+import os
+import sys
+import time
+import scipy
+import struct
+import datetime
+
+#TJP: installed from web python-vxi Alex
+import vxi11
+
+import matplotlib.pyplot as plt
+
+############################################################################
+
+
+############################################################################
+def dmm_init(dmm):
+
+  """
+  Initialize the Digital Multimeter for 4-wire resistance (PT-100) measurement.
+
+    dmm      -- instance of python-vxi connected to the Digital Multimeter
+  """
+
+  dmm =  vxi11.Instrument(args.dmm)    
+  #dmm =  vxi11.Instrument("192.168.32.239")
+  print(dmm.ask("*IDN?"))
+  # Returns 'Keysight Technologies,34465A,MY57501367,A.02.14-02.40-02.14-00.49-03-01'
+
+  # Configure for 4 wire resistance range 100 ohm
+  dmm.write("CONFigure:FRESistance 100")
+  dmm.write("SAMPle:COUNt 1")
+
+  return
+
+############################################################################
+def pt_100(ohm):
+
+  """
+  Calculates the temperature for a given measured PT-100 resistance.
+
+    ohm      -- Ohmic value of the PT-100
+  """
+
+  # Rt = R0.(1 + A.t + B.t^2 + C.(t-100).t^3)
+  R0 = float(100.0)
+  A  = float(3.9083e-3)
+  B  = float(-5.7750e-7)
+  # C = -4,1430e-12 for t < 0 degrees / 0.0 for t >= 0 degrees
+  # For C = 0 =>
+  temp = (-R0 * A + (R0**2 * A**2 - 4 * R0 * B * (R0 - ohm))**0.5)/(2 * R0 * B)
+  return (temp)
+
+############################################################################
+##
+## If run from commandline, we can test the library
+##
+"""
+Usage:
+  Keysight_34465A.py <IP#>
+  Keysight_34465A.py -h | --help
+
+  IP          IP number of the Digital Multimeter
+              (for example: 192.168.32.242 which is its DevNet IP number)
+
+Options:
+  -h --help   Show this screen.
+
+"""
+if __name__ == "__main__":
+    import argparse
+    parser = argparse.ArgumentParser()
+    parser.add_argument("dmm", help="IP-Number of the Digital Multimeter")
+    args = parser.parse_args()
+    print ("Use Digital Multimeter IP address: " + str(args.dmm))
+
+    dmm =  vxi11.Instrument(args.dmm)    
+    dmm_init(dmm)
+    # Returns 'Keysight Technologies,34465A,MY57501367,A.02.14-02.40-02.14-00.49-03-01'
+
+    ohm= float(dmm.ask("READ?"))
+    print(ohm)
+    print(pt_100(ohm))
+    print(pt_100(100))
+    print(pt_100(138.5))
+
+
+    sys.exit()