HP M2350A Service Manual page 72

Understanding the Computer Module
The Function Cards
The interfaces are separated from the CPC so that individual applications do not have to
handle the interfaces. For example, SDN.
Some interfaces have their own connection to the MPB, for example, the RS232 interface card, '-
whereas the other interfaces are local cards located on in the same cluster as the Utility CPU.
Interfaces
The Utility CPU supports a number of interfaces for the HP Component Central Monitor. They
are:
On the CPU board itself:
HP-HIL - for user input/output via the integral keypad and separate keyboard
On local cards:
Rack Interface - to the module rack (maximum of 2 interfaces).
SDN Interface - to an ICWCCU Serial Distribution Network.
HP-HIL
HP-HIL is the Hewlett-Packard Human Interface Link. This is a proprietary interface for
connecting operator input/output devices Examples of supported devices include the Human
Interface Board and a standard keyboard.
The HP-HIL is a serial digital link using a 2-wire bus. The devices are daisy-chained to the
HIL-Master. Each device connected to the system has its own identity which it tags onto its
data.
Each device looks downstream to see if there is any other data present, if this is the case the
device adds its own data to the end of the train or stream of data. This is interpreted by the
HIL-Master on the Utility CPU Card.
Rack Interface
This is a high-speed serial Front-End Link (FE-LINK) for the connection of the module rack.
A locally generated 78-kiloHertz clock is also passed over this interface for module power
synchronization.
A full description of the FE-LINK can be found in the Rack Interface Card functional
description.
SDN Interface
This is a digital network interface used for connecting SDN-equipped devices. This allows the
HP Component Central Monitor access to all the data and status signals on the network.
A fuIl description of the SDN Interface can be found in the SDN Interface Card functional
description.
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