Failed to send framed data: 2 (Udp component)

[gmarchetx]

I'm sure this is a stupid question, but I have been scratching my head for hours with no good leads and I don't think it is too specific so it may benefit people.

I'm connecting Fprime to a third party application, i.e. something that will act as a TCP server for sending telecommands and as a UDP sink for telemetry packets. Our application is set up to use TlmPacketizer, and I have added a Udp component to replace comm for the downlink because the documentation seemed to say the ground side would have to trigger telemetry which I do not want. The uplink is left untouched, and I expect to be able to send commands with the proper protocol through the port given in CLI and it will just work but this is not the scope of this question. Note this is just a demonstration and a test for the other side, so it does not have to be clean, though it is planned for later so feel free to say if anything should be done cleaner still.

I'm starting from the Ref application, here is how our app diverges:

• Top/RefTopology.cpp:
  • Uncommented tlmSend.setPacketList(RefPacketsPkts, RefPacketsIgnore, 1);
  • Added telemComm.configureSend(state.hostname, state.telemPort); next to comm.configure(state.hostname, state.port);
• instances.fpp:
  • Swapped tlmSend from TlmChan to TlmPacketizer
  • Added instance telemComm: Drv.Udp base id 0x4E00 in the passive components
• topology.fpp:
  • Added instance telemComm
  • Renamed comm into telemComm in downlink.framedOut -> comm.$send
  • Renamed comm into telemComm in comm.deallocate -> staticMemory.bufferDeallocate[Ports_StaticMemory.downlink]
• RefPackets.xml:
  • Uncommented <channel name="Ref.tlmSend.SendLevel"/>
  • Removed duplicate <channel name="Ref.cmdSeq.CS_Errors"/> (otherwise the fpp-tools complains)
• Main.cpp
  • Added inputs.telemPort = port_number+1; next to inputs.port = port_number
• RefTopologyDefs.hpp
  • Added U32 telemPort; next to U32 port;

Then I call the application with ./build-artifacts/Linux/Ref/bin/Ref -a "127.0.0.1" -p 50050

And I get the error:

[ERROR] Failed to send framed data: 2

. I traced this back to UdpComponentImpl::send_handler(), fwBuffer.getSize() is 84.

Any idea?

[zimri-leisher]

I have added a Udp component to replace comm for the downlink because the documentation seemed to say the ground side would have to trigger telemetry which I do not want

Not quite sure what you mean by this, TlmPacketizer should send telemetry as often as its run port is called, no triggering from the ground side necessary.

That error can occur for many reasons, it's not very descriptive. I'd recommend going into UdpSocket::sendProtocol and printing the errno after the call to sendto. That should tell you what kind of failure it is--invalid hostname/port, timeout, etc

[gmarchetx]

Thanks for the reply, zimri. What made me switch from the basic setup was that the TCP connection was using a single port for both sending and receiving, which meant some form of coordination that YAMCS's TCP and UDP single-port interfaces certainly don't support. So I basically disconnected the downlink from the TCP comm, and connected it to a UDP sender instead.

I've printed errno where you suggested but it doesn't show for some reason - maybe it fails before going there. The full transcript is:

integration_tests-fprime_app-1 | [ERROR] Failed to send framed data: 2
integration_tests-fprime_app-1 | ---Sending via UDP
integration_tests-fprime_app-1 | [ERROR] Failed to send framed data: 2
integration_tests-fprime_app-1 | [WARNING] Failed to open port with status -4 and errno 111
integration_tests-fprime_app-1 | ---Sending via UDP
integration_tests-fprime_app-1 | [ERROR] Failed to send framed data: 2
integration_tests-fprime_app-1 | [WARNING] Failed to open port with status -4 and errno 111
integration_tests-fprime_app-1 | ---Sending via UDP
integration_tests-fprime_app-1 | [ERROR] Failed to send framed data: 2
integration_tests-fprime_app-1 | ---Sending via UDP
integration_tests-fprime_app-1 | [ERROR] Failed to send framed data: 2
integration_tests-fprime_app-1 | ---Sending via UDP
integration_tests-fprime_app-1 | [ERROR] Failed to send framed data: 2
integration_tests-fprime_app-1 | [WARNING] Failed to open port with status -4 and errno 111
integration_tests-fprime_app-1 | ---Sending via UDP
integration_tests-fprime_app-1 | [ERROR] Failed to send framed data: 2
integration_tests-fprime_app-1 | ---Sending via UDP
integration_tests-fprime_app-1 | [ERROR] Failed to send framed data: 2
integration_tests-fprime_app-1 | [WARNING] Failed to open port with status -4 and errno 111
integration_tests-fprime_app-1 | ---Sending via UDP
integration_tests-fprime_app-1 | [ERROR] Failed to send framed data: 2
integration_tests-fprime_app-1 | ---Sending via UDP
integration_tests-fprime_app-1 | [ERROR] Failed to send framed data: 2
integration_tests-fprime_app-1 | [WARNING] Failed to open port with status -4 and errno 111
integration_tests-fprime_app-1 | ---Sending via UDP
integration_tests-fprime_app-1 | [ERROR] Failed to send framed data: 2
integration_tests-fprime_app-1 | [WARNING] Failed to open port with status -4 and errno 111
integration_tests-fprime_app-1 | ---Sending via UDP
integration_tests-fprime_app-1 | [ERROR] Failed to send framed data: 2
integration_tests-fprime_app-1 | [WARNING] Failed to open port with status -4 and errno 111

The ---Sending via UDP is what I added to UdpComponentImpl::send_handler right before send().
It says here Connection refused, so I tracked what PID was hogging the port, killed it, restarted but it does the same. I also tried with another port, same thing. Any idea?

[ReggieMarr]

I ended up finding the source of the issue, the warning was just a result of not using the correct uplink port with fprime-gds.
The other was a side effect of this recently closed udp issue as well as not opening the udp component after configuring it.

[gmarchetx]

For the warning: The log above was without fprime-gds, because I didn't need it. You're right that I should have thought earlier that these two could just as well be unrelated, since it's only logical it tried to open the TCP port and couldn't because there was no server. It's surprising you got the same warning using fprime-gds though because the uplink port I was using was 50050 which is the default TCP port from/to GDS.

For the error: the documentation of the component doesn't show open() in the example code, and the original Ref code didn't have open() for the TCP component either (they have very similar documentation, when we forget about tasks which are for receiving). Does that mean the documentation of the components is wrong or at least missing information? After all the issue you point to mentions "auto-connect", which might have not worked here.

[LeStarch]

I believe we have captured the need to explicitly open a component when the user is not using the auto-connect feature as part of the SDDs. This was officially release today.

https://fprime.jpl.nasa.gov/v3.6.0/Drv/TcpClient/docs/sdd/#usage

So, yes, the version of the documentation you were consulting was missing this. I believe it has been fixed as shown above.