Andrea C

When running the above code, the following output occurs:

*****
KEITHLEY INSTRUMENTS INC.,MODEL 2636B,4597212,4.0.4

First status byte polling value: 0
0 - 0b0
0 - 0b0
0 - 0b0
0 - 0b0
0 - 0b0
0 - 0b0
0 - 0b0
0 - 0b0
0 - 0b0
0 - 0b0
0 - 0b0
0 - 0b0
0 - 0b0
0 - 0b0
192 - 0b11000000
Test time: 3.765706600010162
Number of actual smua buffer pts: 1.51000e+02

Polling loop done, status byte: 128
Go get the data.
After data downloaded, status byte: 128
Post reset, status byte value: 0

 

In Test Script Builder, look for the samples in folders labeled with 2600 such as KE26XXB_Example_Scripts.

In your post, you are attempting to use commands related to different products/different model numbers which have different command set from what the 2602B understands.

Here is some Python code for use with 2600B to carry out a voltage sweep and measure current.

import pyvisa as visa
import time
import sys
import numpy as np
import matplotlib.pyplot as plt
 
resource_mgr = visa.ResourceManager()
 
try:
     #get a session/handle for one resource
     #change the instrument_resource_string for YOUR INSTRUMENT  
     #instrument_resource_string = "USB0::0x05E6::0x2602::4566591::INSTR"
     instrument_resource_string = "USB0::0x05E6::0x2636::4597212::INSTR"
     #instrument_resource_string = "TCPIP0::192.168.1.208::INSTR"
     my_instr = resource_mgr.open_resource(instrument_resource_string)
except visa.VisaIOError as e:
     #did not connect.....
     print("Whoops, something went wrong")
     #print(e.args)
     #print(resource_mgr.last_status)
     print(resource_mgr.visalib.last_status)
     sys.exit(1)
 
 
# set some parameters for our session
my_instr.timeout = 25000   #timeout in msec
#my_instr.write_termination = '\n'
my_instr.VI_ATTR_TCPIP_KEEPALIVE = True
    
my_instr.write("*IDN?\n")
print("*****")
print(my_instr.read())
 
# set commands to setup a trigger model linear sweep
num_sweep_pts = 151
cmd_list = ["reset()",
            "errorqueue.clear()",
            "smua.source.func = smua.OUTPUT_DCVOLTS",
            "smua.source.limiti = 100e-3",
            "smua.source.rangev = 2",
            "smua.measure.nplc = 1",
            "smua.measure.delay = smua.DELAY_AUTO",
            "smua.measure.delayfactor = 1.0",
            "smua.measure.lowrangei = 100e-9",
            "smua.nvbuffer1.clear()",
            "smua.nvbuffer1.collecttimestamps = 1",
            "smua.nvbuffer2.clear()",
            "smua.nvbuffer2.collecttimestamps = 1",
            "smua.trigger.source.linearv(-1.0, 1.0, " + str(num_sweep_pts) + ")",
            "smua.trigger.source.limiti = 0.1",
            "smua.trigger.measure.action = smua.ENABLE",
            "smua.trigger.measure.iv(smua.nvbuffer1, smua.nvbuffer2)",
            "smua.trigger.endpulse.action = smua.SOURCE_HOLD",
            "smua.trigger.endsweep.action = smua.SOURCE_IDLE",
            "smua.trigger.count = " + str(num_sweep_pts),
            "smua.trigger.source.action = smua.ENABLE"]    
 
for cmd in cmd_list:
    my_instr.write(cmd)    
    
 
#commands to configure SRQ when SWEEPING bit goes 1 to 0 = sweep is finished
# see Chapter 12 in 2600B Reference Manual
cmd_list2 = ["status.reset()",
             "status.operation.enable = status.operation.SWEEPING",
             "status.operation.sweeping.enable = status.operation.sweeping.SMUA",
             "status.operation.sweeping.ptr = 0",
             "status.operation.sweeping.ntr = status.operation.sweeping.SMUA",
             "status.request_enable = status.OSB"]    
 
for cmd in cmd_list2:
    my_instr.write(cmd)
 
 
#turn output on and run the sweep
my_instr.write("smua.source.output = smua.OUTPUT_ON")
 
t1 = time.perf_counter()
 
# important to read stb once before starting trigger model
print("First status byte polling value: " + str(int(my_instr.read_stb())))   
 
#start the trigger model operation
my_instr.write("smua.trigger.initiate()")  
 
# ********************************************
# setup a polling loop to detect Sweep is finished
#repeat until the MSS (SRQ) bit is set
still_running = True
status_byte = 0
debug = 1
 
# attempts to my_instr.query("print(status.condition)") will be blocked by active trigger model task
# instead use my_instr.read_stb() to obtain status.condition register
 
while still_running:
    status_byte = int(my_instr.read_stb())  #read status byte (status.condition register)
    if debug: print(str(status_byte) + ' - ' + str(bin(status_byte)))    
    if (status_byte & 64) == 64:
         still_running = False
    time.sleep(0.25)  #250msec pause before asking again
 
 
#turn output off
my_instr.write("smua.source.output = smua.OUTPUT_OFF")
 
t2 = time.perf_counter()
print('Test time: {}'.format(t2 - t1))
print("Number of actual smua buffer pts: " + str(my_instr.query('print(smua.nvbuffer1.n)')))   
 
print("Polling loop done, status byte: " + str(int(my_instr.read_stb())))     
 
print('Go get the data.')
 
# retrieve data and graph it
 
#ask for voltage and current; buffer2=voltage
my_instr.write("printbuffer(1, smua.nvbuffer1.n, smua.nvbuffer2.readings,smua.nvbuffer1.readings)")
raw_data = my_instr.read()            #one long comma delimited string
 
print("After data downloaded, status byte: " + str(int(my_instr.read_stb())))   
my_instr.write("status.reset()")
print("Post reset, status byte value: " + str(int(my_instr.read_stb())))  
 
# split yields an array of strings alternating voltage, current, voltage, current
raw_data_array = raw_data.split(",")  
 
volts = []
current = []
abs_current = []
 
# step through the array of strings, step size 2
# place the V and I into their own array of floats
for i in range(0, len(raw_data_array),2):
    volts.append(float(raw_data_array[i]))
    current.append(float(raw_data_array[i+1]))
    abs_current.append(abs(float(raw_data_array[i+1])))   #absolute value of currents for log scale
    
#plot the absolute value of current vs. voltage    
plt.plot(volts, abs_current, 'o-g')
 
x_min = min(volts) * 1.1
x_max = max(volts) * 1.1
y_min = abs(min(abs_current)) / 10
y_max = abs(max(abs_current)) * 10
plt.axis([x_min,x_max,y_min,y_max])
plt.yscale('log')
plt.xscale('linear')
plt.title('Sweep V, Measure I, 1MOhm')
plt.margins(x=0.1, y=0.1)
plt.grid(True)
 
plt.show()
 
save_image = 0
if save_image:
    plt.savefig('alc_plot.png')

Can you elaborate on what you mean by it turned into a 2400?

How does the instrument respond to the *IDN? command?  The model number is part of the response string.

Hi Gibbs,

First configure a digital line to give a trigger out when it receives the NOTIFY stimulus.
From the trigger blocks, you can add an entry to use the Notify event to cause the digital IO trigger.

​​​​​​​--setup digital output to strobe when NOTIFY2 event occurs
digio.line[1].mode = digio.MODE_TRIGGER_OUT
trigger.digout[1].pulsewidth = 10e-6
trigger.digout[1].stimulus   = trigger.EVENT_NOTIFY2
 
trigger.model.setblock(blockNumber, trigger.BLOCK_NOTIFY, trigger.EVENT_NOTIFY2)  -- strobe the digital output

 

The trigger lines in the trigger link are 5V, TTL digital lines.

The digital lines are agnostic about what they interface with, so long as they are TTL.

The same steps are required for the 2182A regardless of who’s current source is used.

Does the TDK have digital IO?

For basic communication over LAN, you can use raw sockets or you could obtain a VISA layer from Tek or NI, etc.

The IVI driver for 3706A contains the NI VISA runtime and leverages that for the communication.
There are some .NET examples distributed with the IVI driver.
 

Can you tell us which specific DMM model this is?

Your 37 ohm motor winding is also a big inductor.  Do you have estimate for the L value?
The ohms function is trying to apply a current and measure the V.
When the current is applied, the inductor will cause:  V = L * dI/dt
If this causes max V for the ohms range, I can imagine poor outcomes.

If you have DMM6500, try the diode test function with different current levels.  Any of those stable with your coil?

 

Check your firmware level against what is available for it (1.7.14 now).

I wonder what commands are in use.  If doing a fast trigger model operation, I can envision that front panel processing might slow down.
How do you resolve the freezing?

The DMM6500 can receive ASCII commands on the LAN.  The PLC needs a raw socket connection on port 5025.

Check out the User Manual on Trigger Link.
Also section on stepping and scanning for an idea of how to handshake with external current source.