# Ctrlport\_probe2\_x with gr-ctrlport-monitor in the absence of samples

**URL:** <https://www.ruby-forum.com/t/ctrlport-probe2-x-with-gr-ctrlport-monitor-in-the-absence-of-samples/243241>\
**Category:** GNU Radio\
**Created:** [September 3, 2015, 1:18pm UTC](https://www.ruby-forum.com/t/ctrlport-probe2-x-with-gr-ctrlport-monitor-in-the-absence-of-samples/243241 "2015-09-03T13:18:31Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Sadaf\_N](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/858c86/32.png) [@Sadaf\_N](https://www.ruby-forum.com/u/Sadaf_N)\
**Post date:** [September 3, 2015, 1:18pm UTC](https://www.ruby-forum.com/t/ctrlport-probe2-x-with-gr-ctrlport-monitor-in-the-absence-of-samples/243241/1 "2015-09-03T13:18:31Z")

</div>

I’m attempting to use ctrlport\_probe2\_x and gr-ctrlport-monitor to probe  
points in a bursty flowgraph. When I place a ctrlport\_probe2\_x probe  
somewhere in the part of my flowgraph that process samples only upon  
reception of a burst, gr-ctrlport-monitor doesn’t fully initialize  
(populate its list of controlport “knobs”) until after all  
ctrlport\_probe2\_x blocks have performed at least one call to work().  
Furthermore, the gr-ctrlport-monitor GUI is only responsive to user  
input  
if all ctrlport\_probe2\_x blocks in the flowgraph are regularly making  
calls  
to work() (i.e. gr-ctrlport-monitor query latency becomes equal to the  
time  
that elapses between processing individual bursts), so if for some  
reason  
bursts ever stop trickling to one of the probes, gr-ctrlport-monitor  
becomes unresponsive to user input.

The gr-ctrlport-monitor behavior can be recreated with any simple  
flowgraph  
that contains a ctrlport\_probe2\_x that will never (or infrequently) make  
a  
call to work, such as: random\_pdu -\> pdu\_to\_tagged\_stream -\>  
ctrlport\_probe2\_b, where the “generate” port of the random\_pdu block is  
left unconnected. Attempting to connect gr-ctrlport-monitor to this  
flowgraph will cause gr-ctrlport-monitor to be unresponsive (have to  
kill  
it) almost immediately after the GUI is displayed.

I wasn’t sure if this is a limitation of ctrlport\_probe2\_x or  
gr-ctrlport-monitor, but I wanted to see if t was was possible to make  
the  
combination play nicely together when applied to a bursty flowgraph.

Relevant system info:  
GNU Radio 3.7.8  
Thrift 0.9.2  
Ubuntu 15.04

Thanks in advance,  
Eric