Re: [Discuss-gnuradio] Reconfiguring OFDM flow graph at run time gives "FATAL: Missing a required length tag on port 0 at item" error

2016-12-24 Thread Damindra Bandara
Dear Dat, You are correct. When I create a new tagged stream block and connect to the flow graph the problem was fixed. Thank you for the suggestion. I will see how to write a similar block to handle the problem. Damindra On Sat, Dec 24, 2016 at 3:43 PM, Dat Luu wrote: > I think you use a set

Re: [Discuss-gnuradio] Reconfiguring OFDM flow graph at run time gives "FATAL: Missing a required length tag on port 0 at item" error

2016-12-24 Thread Dat Luu
I think you use a set up like this * -- stream to tagged stream -- ofdm tx -- * and then perform event triggering (time based by sleep function?) to do reconfiguring? If yes, the problem is with the tagged stream block and stop(); the block will not add any tag to data stream it was processing upon

Re: [Discuss-gnuradio] Reconfiguring OFDM flow graph at run time gives "FATAL: Missing a required length tag on port 0 at item" error

2016-12-24 Thread Damindra Bandara
Dear Keven, Please consider the following flow graph. I have done some changes to the OFDM TX block and in the earlier file forgot to remove that. This file has all the original GNURadio blocks and running in no GUI mode. But still the problem is there. I appreciate if you could help me to figure

Re: [Discuss-gnuradio] Reconfiguring OFDM flow graph at run time gives "FATAL: Missing a required length tag on port 0 at item" error

2016-12-24 Thread Damindra Bandara
Dear Kevin, Thank you for your response. Here are the answers to the questions you asked. Does it happen if you only stop and start the flow graph without actually changing any connections? Yes. It still gives the same error when only stop and start the flow graph. When I do the reconfiguration

Re: [Discuss-gnuradio] Reconfiguring OFDM flow graph at run time gives "FATAL: Missing a required length tag on port 0 at item" error

2016-12-24 Thread Kevin Reid
On Sat, Dec 24, 2016 at 9:46 AM, Damindra Bandara < damindra.band...@gmail.com> wrote: > > Also, I get the error only when I try to reconfigure a flow graph. Could > you please let me know the correct way to reconfigure a flow graph when > they are using tags. > Both reconfiguration and tags are l

Re: [Discuss-gnuradio] Modifying OFDM-TX block get an additional output

2016-12-24 Thread Damindra Bandara
Thanks Karthik, I figured that out too. I am using it in my code. On Sat, Dec 24, 2016 at 1:47 AM, Kartik Patel wrote: > Hi Damindra, > > For this problem, we have a better approach. Since, both output ports in > your block are homogeneous (i.e. both types are same) it is preferred to > use *gr.

Re: [Discuss-gnuradio] Reconfiguring OFDM flow graph at run time gives "FATAL: Missing a required length tag on port 0 at item" error

2016-12-24 Thread Damindra Bandara
Dear Kartik, The length tag name in the OFDM transmitter and the Length Tag key parameter in Stream to Tagged Stream block is the same.It is set properly. Also, I get the error only when I try to reconfigure a flow graph. Could you please let me know the correct way to reconfigure a flow graph wh

Re: [Discuss-gnuradio] Reconfiguring OFDM flow graph at run time gives "FATAL: Missing a required length tag on port 0 at item" error

2016-12-24 Thread Kartik Patel
Hi Damindra, In the OFDM Transmitter block, check the parameter Length Tag Name. Value of that parameter should be same as Length Tag Key parameter in Stream to Tagged Stream block. See gr-digital/examples/ofdm/tx_ofdm.grc for an example. Regards,Kartik Patel On Sat, Dec 24, 2016 4:19 AM,