How to correct the trouble: D9210 #x OPEN.

What does it mean when the D1255 Keypad displays [D9210 #1 OPEN] or [D9210 #1 OPEN WIRE]?

D9210 #1 OPEN means the the Yellow SDI Buss A Data wire is open between the panel and the D9210 addressed as 1.

B901, D9210C, D9210B