StorageTek 9710 - Manual (Page 40)

SCSI Library Robotic Interface
3-12 9710 System Assurance Guide MR0012J
Note: The 3270 control interface ports shown in Figure 3-8 on page 3-12 are
not presently used. One of the two SCSI control interface ports is used
for the control line; the other is reserved for daisy chaining.
Figure 3-8. 9710 I/O Panel (Showing Fibre Channel)