What value?

You have a control input (Send or Receive) and a couple of data input/output.

When you send data, regardless if it is 1 or 0, you make control input high. This input is control not data. Your data can be 1 or 0. When you are done with data, then control input is set to low again, and you are ready to get any valid data.

In reallity the chip has 2 control pins and 2 data pins. Control are anti phase active so you can connect them together. Data can only be sent or received. Not at the same time if you have only one couple of lines (A-B), so you can connect data in and data out together too.

Ioannis