How to set a variable interval time in echoClient?

[weilin zhong]

Hi all. I have a question that how to set a variable interval time in echoClient. 

In some case, I want to set the interval time as a variable but not a constant like 1s, 2s... In other words, I want to send packets when there is an external request, like sending packets step by step from t(i-1) to t(i). I've made a little bit change in first.py by adding a for loop in the script but it didn't work. It seems the echoClient.SetAttribute is an Integral function. Here are my code and result. 

Can anybody give me a hand with it? Thank you very much.

Weilin