Receiving a Byte From a Slave Device
Once the slave has been addressed and the slave has acknowledged this, a byte can be received from the slave if the R/W bit in the address was set to READ (set to '1').
The protocol syntax is the same as in transmitting a byte to a slave, except that now the master is not allowed to touch the SDA line. Prior to sending the 8 clock pulses needed to clock in a byte on the SCL line, the master releases the SDA line. The slave will now take control of this line. The line will then go high if it wants to transmit a '1' or, if the slave wants to send a '0', remain low.
All the master has to do is generate a rising edge on the SCL line (2), read the level on SDA (3) and generate a falling edge on the SCL line (4). The slave will not change the data during the time that SCL is high. (Otherwise a Start or Stop condition might inadvertently be generated.)
During (1) and (5), the slave may change the state of the SDA line.
In total, this sequence has to be performed 8 times to complete the data byte. Bytes are always transmitted MSB first.
The meaning of all bytes being read depends on the slave. There is no such thing as a "universal status register". You need to consult the data sheet of the slave being addressed to know the meaning of each bit in any byte transmitted.