# Runtime error - Empty Device Address in GRC Flowgraph build

**URL:** <https://www.ruby-forum.com/t/runtime-error-empty-device-address-in-grc-flowgraph-build/243020>\
**Category:** GNU Radio\
**Created:** [August 15, 2015, 1:02pm UTC](https://www.ruby-forum.com/t/runtime-error-empty-device-address-in-grc-flowgraph-build/243020 "2015-08-15T13:02:49Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Rafa\_F](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/958977/32.png) [@Rafa\_F](https://www.ruby-forum.com/u/Rafa_F)\
**Post date:** [August 15, 2015, 1:02pm UTC](https://www.ruby-forum.com/t/runtime-error-empty-device-address-in-grc-flowgraph-build/243020/1 "2015-08-15T13:02:49Z")

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Hello,

After installing GRC into Ubuntu 15.05 64bit I get the following error  
when trying to run a GRC flow graph example:-

* * *

RuntimeError: LookupError: KeyError: No devices found for -----\>  
Empty Device Address

* * *

A uhd\_find\_device command successfully returns the serial number from my  
USRP B100 in TERMINAL. However, as I say, the flowgraph wont build as it  
doesn’t appear to be able to locate my USRP B100 via its USB connection.

“uhd\_images\_downloader.py” successfully runs and running uhd-usrp.rules  
to moves rule file to /etc/udev/rules.d/ carries out ok too.

However, again, I’m still unable to build a successful GRC flowgraph  
with my B100.

I leave the device address empty in the GRC UHD USRP Source block but  
again, GRC wont build the flowgraph and returns the above error message.

Please help as I’ve spent days trying to get GRC to install and operate  
successfully.

Many thanks in advance,

Mark

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**Author:** ![markh](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/7993a0/32.png) [@markh](https://www.ruby-forum.com/u/markh)\
**Post date:** [August 15, 2015, 7:52pm UTC](https://www.ruby-forum.com/t/runtime-error-empty-device-address-in-grc-flowgraph-build/243020/2 "2015-08-15T19:52:19Z")

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When running uhd\_find\_devices, do you happen to use “sudo”?

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**Author:** ![markh](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/7993a0/32.png) [@markh](https://www.ruby-forum.com/u/markh)\
**Post date:** [August 15, 2015, 7:31pm UTC](https://www.ruby-forum.com/t/runtime-error-empty-device-address-in-grc-flowgraph-build/243020/3 "2015-08-15T19:31:16Z")

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On 08/15/2015 06:58 AM, Mark wrote:

> Many thanks in advance,
> 
> Mark
> 
> * * *
> 
> Discuss-gnuradio mailing list  
> [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)  
> [Discuss-gnuradio Info Page](https://lists.gnu.org/mailman/listinfo/discuss-gnuradio)  
> Have you tried just putting a device address in?

use:

type=b100

in the device address field in your flow-graph