 1.Do you used hardware protocol or software protocol2.protocol and cable have to compatible. 3.software protocol you can shortage 4-5 , 6-8-20 at cnc (25 pin ) 4.hardware protocol cnc 4-- pc 5, cnc 5-- pc 4. and cnc side 6-8-20 jumper 5. ic circuit was broken. 6.simplest way to check handshake signals, you can make a plug according 4-5 , 6-8-20 jumpered and put on cnc system. And then push read button. (no computer) If handshake signal is ok fanuc system will flash LSK or EDIT as like as cnc system is reading and cnc no alarm. Sorry my poor english! | 
Computer Numerical Control
