2.0 Features of the S-LINK
1. Flow Control: The ROMB can assert a signal, UXOFF#, at the LDC which causes it to transmit an XOFF code to the LSC. This stops data transmission from the LSC. When the signal is de-asserted, an XON code is transmitted to the LSC which allows transmission to resume.
2. Return Lines: The state of four lines is continually sampled at the LDC, transmitted back to the LSC and presented to the FEMB. To the user, this looks like four wires running back from the LDC to the LSC.