Adaptec 2940 Installation Guide - Page 5

s If the AHA-2940 detects that a cable is connected to both its internal and external SCSI connector, then it disables its terminators (the AHA-2940 lies between the ends of the SCSI bus). We recommend that you leave the AHA-2940 set to its default setting of Automatic. If you want to manually enable or disable the AHA-2940 termination setting, see Configuring the Host Adapter on page 8. Terminating the AHA-2940W Termination on the AHA-2940W itself is also controlled by software commands via the SCSISelect utility. The default setting is set to Low ON/High ON. This means that termination is enabled for both the low and the high bytes of the 16-bit Wide SCSI bus. The low byte controls the 8-bit SCSI; the low and high bytes together control 16-bit Wide SCSI. If you are using both internal connectors on the AHA-2940W, or an internal connector and the external connector, you must change the termination setting from the default setting. The following table lists the termination configurations. Devices Connected to AHA-2940W 68-pin internal connector only 68-pin external connector only 68-pin internal and 68-pin external connectors 50-pin internal connector only 50-pin and 68-pin internal connectors 50-pin internal and 68-pin external connectors AHA-2940W Termination Low High ON ON ON ON OFF OFF ON ON OFF ON OFF ON Terminating SCSI Devices Read the device's documentation to determine how to enable or disable termination on your particular SCSI device(s). On most internal SCSI devices the termination setting is controlled by a jumper or a switch. On other internal SCSI devices you must physically remove or install resistor module(s). On most external SCSI devices, a terminating plug (a resistor pack embedded in a small plug) is installed or removed to control termination. 4 Downloaded from www.Manualslib.com manuals search engine