connections for 7i97t

What connections does the 7i97t board need to servo motors to operate?

(as+, da+) analog command voltage,
(gnda, da ground) analog ground,
(SON) servo enable,
(rdy) servo ready,

(oa+)A+
(oa-)A-
(ob+)B+
(ob-)B-
(oz+)Z+
(oz-)Z-
 

7I97T     DRIVE CN1
AOUTN   AS+ (26)
GND       GNDA (11)
ENAN+  SON  DI1 (16)
ENAN-    24V Common
INN         RDY  DO1 (20)
INCOM    +24V  (Drive output common 24V common)   

QAN+       OA+  (13)
QAN-         OA-   (28)
QBN+       OB+  (14)
QBN-         OB-  (29)
QIDXN+    OZ+ (15)
QIDXN-      OZ-  (30)
 

Is z encoder output signal and encoded signal to ground needed?

The "Z" signals are needed if you want to home to index.
(for more accurate homing)

Yes, normally you would connect the encoder ground at both the
drive and 7I97T end.