Thank you for responding, the real direction is 0x70 using 7 bits. In other words is 111-0000. If I include the bit of R/W, this will be 0 if i want to write a data in the slave(sensor). .111000-R/W ----------> 11100000 11100000 Is E0 in hex. For this reason, I have several concerns about this module, but I hope to solve it later. Thans again for taking my doubt. I will try to send you 6 bits as data and include the CRC byte. It is likely that when I insert the writeBytes command, the R/W bit is inclued internally without me noticing.