# Gr-uhd multi\_usrp bug in 3.7.4+

**URL:** <https://www.ruby-forum.com/t/gr-uhd-multi-usrp-bug-in-3-7-4/231894>\
**Category:** GNU Radio\
**Created:** [September 4, 2014, 6:19pm UTC](https://www.ruby-forum.com/t/gr-uhd-multi-usrp-bug-in-3-7-4/231894 "2014-09-04T18:19:22Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![addis\_a](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/c4cdca/32.png) [@addis\_a](https://www.ruby-forum.com/u/addis_a)\
**Post date:** [September 4, 2014, 6:19pm UTC](https://www.ruby-forum.com/t/gr-uhd-multi-usrp-bug-in-3-7-4/231894/1 "2014-09-04T18:19:22Z")

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Hi,

Looks like either the syntax for instantiating multi\_usrp has changed  
(seems unlikely), or a bug was introduced, likely in 7/2-7/4’s recent  
gr-uhd refactoring (1eaa96b, 350d285, fe58537, 3c42e79, 691bdaa). Sorry  
I  
haven’t gotten more specific than that. The attached flowgraph, when  
used  
with a USRP1 (yes, I know, I’m probably the only guy using one) returns:

RuntimeError: LookupError: IndexError: multi\_usrp: TX channel 1 out of  
range for configured TX frontends

Prior to the above commits the error does not occur.

Best,  
Nick

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**Author:** ![nickfaraday](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/b2d939/32.png) [@nickfaraday](https://www.ruby-forum.com/u/nickfaraday)\
**Post date:** [September 7, 2014, 11:40am UTC](https://www.ruby-forum.com/t/gr-uhd-multi-usrp-bug-in-3-7-4/231894/2 "2014-09-07T11:40:38Z")

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On 09/04/2014 06:17 PM, Nick F. wrote:

> Prior to the above commits the error does not occur.  
> I tried replicating this, not successfully. I don’t have a USRP1,  
> though. On an X300, it works fine.

Let’s take this discussion to the bug you filed.

M

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**Author:** ![nickfaraday](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/b2d939/32.png) [@nickfaraday](https://www.ruby-forum.com/u/nickfaraday)\
**Post date:** [September 27, 2014, 10:46pm UTC](https://www.ruby-forum.com/t/gr-uhd-multi-usrp-bug-in-3-7-4/231894/3 "2014-09-27T22:46:55Z")

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On 09/07/2014 05:38 AM, Martin B. wrote:

> > 
> 
> 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)

This also happens on a B100 with a TVRX2 card

–  
Marcus L.  
Principal Investigator  
Shirleys Bay Radio Astronomy Consortium

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