TDMA using TREK1000 source code

Hello. Im have few EVB1000 boards and want to build small network using TDMA to collect information from nodes(anchors in TREK1000 example) to coordinator(tag). In my use case network is simple (1coord - 3 nodes with 40 byytes payload) and timings of superframe of example is enough. Im trying to understand code of example.
As i understood the main function is

testapprun(instance_data_t *inst, int message)

sended data stored in

srd_msg_dsss messageData[MAX_USER_PAYLOAD_STRING_SS]

but i can’t understand how to fill this buffer with my own data? I found that response from anchor prepared by


Can this example(TREK1000) be used to transmit data using TDMA? Or is there any implementation of TDMA MAC, which can be used for a hot start on EVB 1000?