In a half-duplex write mode, the master sends data on the MOSI line and the slave receives it. The MISO line remains inactive.
To send data in a half-duplex mode, use the DlnSpiMasterWriteEx() function. This function allows to configure whether the SS line should be released after the transmission or left on the low level.
In a half-duplex mode, the master can send data to multiple slaves simultaneously. For details, read Connecting Multiple Slave Devices.