How to config TCP transport using RTI DDS Toolkit for Labview？

[saiyxin]

Hello，I have learned that DDS communication across WAN using UDP by default，since UDP is an unreliable transport protocol，is it possible to loss date even though DDS has some retransmission mechanism？In order to make data transmission more reliable，I want to config DDS communication using TCP transport, so how to do it using RTI DDS Toolkit for Labview？Is there any Labview examples？

[ismaelrti · Accepted solution]

Hi saiyxin,

It is possible to use the TCP transport with the DDS LabVIEW Toolkit. It requires an additional library called nddstransporttcp.dll. That library is not included by default with the toolkit. You need to get from a Connextdds installation folder after installing the target libraries of the following architecture depending of the Toolkit version you are using (available at <connextdds installation folder>/lib/<architecture>):

- DDS LabVIEW Toolkit version 3.1.1: i86Win32VS2015 for Windows LabVIEW 32 bits or x64Win64VS2015 for Windows LabVIEW 64bits.

- DDS LabVIEW Toolkit version prior to 3.1.1: i86Win32VS2010 for Windows LabVIEW 32.

The library nddstransporttcp.dll must be in <LabVIEW installation folder>\vi.lib\_RTI DDS Toolkit_internal_deps. Since it is dynamically loaded it must be added to the PATH environment variable.

Once the library is properly placed, you need to set the QoS for using it. Follow this link to learn how to do it. Remember that in case you need to specify the discovery peers you can do it by using the environment variable NDDS_DISCOVERY_PEERS=<remote IP>. You have more information here.

Regards

Ismael

[saiyxin]

Hi, Ismaelrti

So what is the difference between UDP transport and TCP transport in DDS communication？How to config the QoS Profile by Labview？Is it necessary to modify the QoS profiles XML？

[ismaelrti]

Hi Saiyin,

UDP is fine for communicating with systems on the same network. But it presents some issues when communicating with systems on different networks like NATS. In this link, you can find more information about it and you can see the scenarios on which you can take advantage of using TCP.

Regarding how to configure the QoS in the LabVIEW toolkit you have it documented in the Getting Started Manual. You can find it In the LabVIEW window Help->RTI DDS Toolkit->Open Getting Started Guide. In that document go to section Chapter 5 "Loading Quality of Service Profiles".