Problem connecting to BK Precision OhmMeter

[Denis Barkats]

Hi all, 

I have a  2841 BK Precision microOhmMeter (https://www.bkprecision.com/products/component-testers/2841). 

I have installed the usbtmc python library (details here:https://github.com/python-ivi/python-usbtmc) on my Mac osx and I can load the library fine (import usbtmc work).

When I query my mac for usb devices ( "ioreg -p IOUSB -w0 -l"), I can see the 2841 ohm meter when it is connected via USB. ( see result below)

   +-o 2841@14100000  <class AppleUSBDevice, id 0x10009c2b8, registered, matched, active, busy 0 (36 ms), retain 21>

        {

          "sessionID" = 2569533099887384

          "iManufacturer" = 4

          "bNumConfigurations" = 1

          "idProduct" = 5894

          "bcdDevice" = 256

          "Bus Power Available" = 250

          "USB Address" = 22

          "bMaxPacketSize0" = 64

          "iProduct" = 32

          "iSerialNumber" = 68

          "bDeviceClass" = 2

          "Built-In" = No

          "locationID" = 336592896

          "bDeviceSubClass" = 0

          "bcdUSB" = 512

          "USB Product Name" = "2841"

          "PortNum" = 1

          "non-removable" = "no"

          "IOCFPlugInTypes" = {"9dc7b780-9ec0-11d4-a54f-000a27052861"="IOUSBFamily.kext/Contents/PlugIns/IOUSBLib.bundle"}

          "bDeviceProtocol" = 0

          "IOUserClientClass" = "IOUSBDeviceUserClientV2"

          "IOPowerManagement" = {"DevicePowerState"=0,"CurrentPowerState"=3,"CapabilityFlags"=65536,"MaxPowerState"=4,"DriverPowerState"=3}

          "kUSBCurrentConfiguration" = 1

          "Device Speed" = 1

          "USB Vendor Name" = "BK Precision"

          "idVendor" = 49745

          "IOGeneralInterest" = "IOCommand is not serializable"

          "USB Serial Number" = "482A16001"

          "IOClassNameOverride" = "IOUSBDevice"

        }

However, when I try to load the device with the usbtmc library, I can't get it, and I tried all combinations of idVendor and idProduct numbers:

instr = usbtmc.Instrument(49745,5894)

 Device not found [init]        

Any suggestions would be welcome!

Thanks

[Denis Barkats]

To add more info to my own question.

I downloaded the mac equivalent of lsusb and I clearly see the device:

lsusb -v

        2841:

          Product ID: 0x1706

          Vendor ID: 0xc251

          Version: 1.00

          Serial Number: 482A16001

       But then it still doesn't seem visible  at all by the usbtmc library

In [4]: usbtmc.list_devices()

Out[4]: []

Any ideas ?

[Denis Barkats]

Ok, I resolved the problem.

The device in  question has multiple communication options. I had to go in that setup and set the communication option to "USBTMC". Unplug the device and re-plug it in and the idVendor and idProduct changed.

Now it works.

In [7]: instr = usbtmc.Instrument(1137,9493)

In [8]: usbtmc.list_devices()

Out[8]: [<DEVICE ID 0471:2515 on Bus 020 Address 029>]

In [9]: instr.ask("*IDN?")

Out[9]: 'B&K Precision,2841,482D22102,1.7.2'