There isn't an event for reading data, Synapse uses another reading design!
Other asynchronous packages have an event, which is called if some data arrived. You must implement this event, read all the data into your buffers, and then your application logic must parse this data.
In Synapse another logic is used. There is no event! All the data is read at the moment when your application logic needs data. Simply, you implement your application logic in this style: “I need to send data, simply call command for send. I need to receive some data, simply call command to receive this data.”
See more in ReadData how-to.