Multiple USB IEEE-488 devices on one PC

[trdoran]

We are trying to run multiple USB IEEE-488 devices on one PC. Whenever we connect more than one, the PC runs un-usably slow. Can someone help us out on why this is?

[Stuart M]

Not sure whose problem this is. Need detailed information. What is your specific setup...?

Which GPIB cards or interfaces are installed?
What version of GPIB driver?
What operating system?
What software program(s) are you running that seem to be running slow?

[trdoran]

We designed an interface device to load and debug software we write into a aircraft computer system. The communication is KUSB-488B based. We are required to load and debug four systems at a time. The original design utilized four PCI based 488 cards. The system worked well. Later we moved to the USB version of the 488 interface. This is where we have run into issues. Whenever we have more than one of the USB 488 devices installed, it runs extremely slow.


Device part number: KUSB-488B
Driver: Version 7.0.0.0 taken from the 3.12 driver disk
Operating system: Windows 7 64 bit
We are running a locally developed program

Have you ever run with more that one USB 488 device running on the same PC?

Timothy Doran
Systems Integration Lab Manager
The Boeing Company

[brian.d.smith]

I have controlled a model 236 and a model 237 with a KUSB-488B using Python. The model 237 is at GPIB address 1. The model 236 is at GPIB address 17.

Code: Select all

#  Curve trace program for Keithley 236/237/238 Source Measure Units (SMUs)
#  SMU A controls the drain of a FET   SMU B controls the gate
#

import visa                                      #import NI Virtual Instrument Software Architecture
import time                                      #import python time functionality
A = visa.instrument("GPIB::1")                  #create variable for instrument address
B = visa.instrument("GPIB::17") 
                                                                 #variable for voltage
stepvoltage = -1.0
sweeploopcount = 16
steploopcount = 5
sweepresults = []                                     # create list to store measurements
A.write("F0,0X")                                 # Force Force V measure I
A.write("H0X")                                   # Immediate trigger
A.write("G5,2,0X")                               # source and measure
B.write("F0,0X")                                 # Force Force V measure I
B.write("H0X")                                   # Immediate trigger
B.write("G5,2,0X") 
                                                 #Bias voltage , auto range, no delay
B.write("N1X")  

for j in range(steploopcount):  
    sweepvoltage = 0   
    stepvoltage = stepvoltage + 1.0
    B.write("B" +str(stepvoltage) +",0,0X") 
    for i in range(sweeploopcount):                             #loop variable and loop count
        A.write("B" +str(sweepvoltage) +",0,0X")          #Bias voltage , auto range, no delay
        A.write("N1X")                               # Operate (output on)
        sweepvoltage = sweepvoltage + 1                      #increment voltage
        time.sleep(0.05)                             # Wait
        sweepresults.append(A.read())                     # read measurement from SMU
        time.sleep(0.05)                             # Wait

# print results[i]                             #print measurement to console
A.write("N0X")                                   # Standby (output off)
B.write("N0X") 
print "Rdg","Voltage","   Current"
print " "
for i in range(sweeploopcount*steploopcount):
    print i,sweepresults[i]                           #print list of measurements
time.sleep(5) 

[brian.d.smith]

I sent you a private message with my contact information. Please respond and we can start working on your problem.

[Stuart M]

There are several fixes made to the driver in version 3.12.1 which you might want to - up.

Available for download from here:
http://www.keithley.com/support/data?asset=56984
(Would also suggest using NI Command Compatible mode).