Siemens SIMATIC RI 45 PIII Series Manual page 112

SCSI Option
Figure 7-1
8-bit SCSI devices have a 50-pin connector, and 16-bit SCSI devices have a
68-pin connector.
You need an adapter (68-pin to 50-pin) if you want to connect 8-bit SCSI
devices to the SCSI controller.
If you are operating an 8-bit SCSI device as the final device on the SCSI
cable you need an adapter (68-pin to 50-pin) with high-byte termination.
Caution
!
Use top-quality SCSI cables only as otherwise you may have problems
transferring data.
7-4
internal 16-bit
68-pin connector
external 16-bit
68-pin connector
4-pin LED
connector
internal 8-bit
50-pin connector
RI 45 PIII, Manual
C79000-G7076-C817-01