Figure 19 illustrates the internal register structure of the TMP43x. The 8-bit Pointer Register is used to address a given data register. The Pointer Register identifies which of the data registers must respond to a read or write command on the Two-Wire bus. This register is set with every write command. A write command must be issued to set the proper value in the Pointer Register before executing a read command. Table 3 describes the pointer address of the registers available in the TMP431. Table 4 describes the address of the registers available in the TMP432. The power-on reset (POR) value of the Pointer Register is 00h (0000 0000b).