MSP430 multiple slaves in SPI communication
A number of SPI slaves can be connected in one of two configurations:

Single Slave-Select daisy-chained



Here the entire SPI bus is treated as one big shift register and the master must know the order of devices in the bus chain and their respective register widths.  It is also necessary to write all devices at the same time in the same bus transaction.  Often the /SS line in this case is controlled by the SPI peripheral controller. 

Independent Slave-Selects - wire-OR'ed MISO/MOSI



Here each device can be selected and written to independently at any time.  Normally the /SSn lines are under software control and the master can select and access each device at any frequency and in any order.

The first configuration requires that each slave has a MISO. Some "write-only" devices such as 7 segment displays lack an MISO so can only share an SPI wired as in the second case, where such devices will not be connected to MISO.