Hi Sanjay,
You can measure the time delay between the control signal and the relay output in usb 6229 counter inputs.
In order to do that select Acquire signals>>counters>>Two edge separation. USB 6229 has 2 counter inputs. Wire in the control signal as well as the relay output to the 2 counters. Select the voltage levels and other settings in DAQmx assistant as shown below. The number of counts will give you the time lag in your relay application.

Hope that solves your Querry.
Regards,
Shreyas
Shreyas Hebbare
Shreyas Technologies
India