Remote reading SDcard from Arduino+Wireless Shield + XBee s2


I have created my ZigBee network with this stuff: 2x Arduino UNO + 2x Wireless Shield + 2x XBee s2, so i have checked that my network is ok, coordinator can communicate with end device and vice versa.

My first arduino (End device) is connected to 2 sensors (luminosity and temperature) and it's saving the data to SDcard on local Wireless Shield. So, my question is how can i access remotely to that SDcard (to saved file log.txt in it) from my other arduino (coordinator) .

Best regards.