Asus AP2500 SCSI Cable Limits, NOTE:, NOTES:, - 1.5m, - 1.5m, (9.8ft), (9.8ft), Appendix, CAUTION:, A total of, A total of, A total of, A total of, Max Devices

III. Appendix

Appendix .III

SCSI Cable Limits

SCSI cables have a limit to the length that it may have. Exceeding the length may cause problems mounting or using any one of the SCSI devices.

CAUTION: Exceeding the SCSI cable limits may cause unreliable data transfers even if all the devices are mounted properly.

NOTES:

• Narrow refers to 50 pin and Wide refers to 68 pin. Don’t get confused by the width of the connector or cable.

•The SCSI ID for devices on one connector cannot be the same as the SCSI ID for devices on the other connectors. None of the devices on any connector can use ID7, which is reserved for the SCSI controller.

•A maximum of15 devices may be connected to the motherboard (three connectors) at one time. The following “Max Devices” are for individual connectors and do not take into account other SCSI devices.

Cable Limits			Max Data Transfer Rates	Max Devices
1)	12m (29.4ft)		Ultra2-SCSI (68 pin 80MB/Sec)		15
2)	3m	- 1.5m	Wide Ultra-SCSI (68 pin 40MB/Sec)		4 - 8
3)	3m	(9.8ft)	Wide-SCSI (68 pin 20MB/Sec)		15
4)	3m	- 1.5m	Narrow Ultra-SCSI (50 pin 20MB/Sec)		4 - 7
5)	3m	(9.8ft)	Narrow Fast-SCSI (50 pin 10MB/Sec)		7

Notes for the above chart:

1) A total of 15 “Ultra2-SCSI” devices (ID0-ID15) may be connected to the 68-pin Ultra2 connector on the motherboard.

NOTE: If connecting Fast/Ultra devices with Ultra2 devices on the Ul- tra2 connector, the entire SCSI bus will be limited to the Ultra SCSI conditions listed above. Mixing SCSI devices is highly not recommended.

2)A total of 8 “Wide Ultra-SCSI” devices (ID0-ID15) may be connected to the 68-pin Wide connector if using a 1.5m (4.9ft) cable, but only 4 “Wide Ultra-SCSI” devices if using a 3m (9.89ft) cable. Ultra-SCSI technology is unstable over long lenghts, therefore stability will depend on they qual- ity of your cable and devices.

3)A total of 15 “Wide-SCSI” devices (ID0-ID15) may be connected to the 68-pin Wide connector.

4)A total of 7 “Narrow Ultra-SCSI” devices (ID0-ID6) may be connected to the 50-pin Narrow connector when using 1.5m (4.9ft) cable but only 4 devices when using 3m (9.8ft) cable. Ultra-SCSI technology is un- stable over long lengths, therefore stability will depend on the quality of your cable and devices.

5)A total of 7 “Narrow Fast SCSI” devices (ID0-ID7) may be connected to the 50-pin Narrow connector.

36 AP2500 Hardware Reference Guide