Re: [Discuss-gnuradio] len_tag_key

[Martin Braun]

On 06/29/2014 10:49 AM, GP 2014 wrote:
> Dear all ,
> I use a flowgraph containing : File source , OFDM TX ,throttle, File
> sink (I will replace then the file sink by UHD sink to try with USRP)
> I got this error message
> 
> FATAL: Missing a required length tag on port 0 at item #0
> thread[thread-per-block[1]: <block crc32_bb (14)>]: Missing length tag.
> 
> I tried to solve this problem but I failed :
> in TX in the field called length tag name ,
> I tried  to write same input to this field as in the loopback :
> I wrote in this field : len_tag_key
> Then I put a variable block with ID :len_tag_key , with value : "packet_len"
> Then I put another variable block with ID: packet_len , with value:87
> 
> Also I tried to write in this field : packet_len & put only one variable
> block with ID packet_len & value:87 .. I got the same error !!
> What is must be written in this field ?!!!

You must provide a key for the tagged stream tags. Read
http://gnuradio.org/doc/doxygen/page_tagged_stream_blocks.html and the
OFDM examples.

M