HP manual Connecting the HP E8491A to the Host Adapter

C. Tighten the retaining screws on the top and bottom of the module.

Connecting the HP E8491A to the Host Adapter

D.Connect the interface cable from the host adapter to E8491A port A, B, or C. The ports are identical and unused ports are available to connect additional E8491As and other IEEE 1394 devices in a daisy-chain or tree configuration (Figure 2-7). Notice that there can be no closed loops.

DAISY-CHAIN CONFIGURATION	TREE CONFIGURATION
PC		PC
VXI
	VXI	VXI

VXI

*

VXIVXI

VXI

*A second connection creates a closed loop and is not allowed

Figure 2-7. IEEE 1394 Interface Configurations.

I/O performance is impacted slightly by the hardware configuration.The VXI mainframe with the fewest number of hops (cable links) to the PC has the highest priority. However, each mainframe has equal access to the bus during each data transfer interval.

Note Refer to Chapter 4: IEEE 1394 Fundamentals and Interface Overview for information on the topology and terms associated with the IEEE 1394 bus.

Alternate Configurations Certain applications may include the HP E1406A Command Module as an HP-IB interface to selected instruments. In this configuration, the E8491A must be the resource manager since its logical address is always 0. It is generally installed in mainframe slot 0 so that it also provides the system’s slot 0 functionality.

Chapter 2 Interface Installation and Configuration 19