GB2202062A - Checking a system configuration - Google Patents

Abstract

To enable a hardware configuration check to be carried out, each circuit card type is allocated a predetermined code which is hard-wired into the card during manufacture. A central configuration map is stored in a central processor (7) which downloads segments of that map to each card-containing shelf (2) in the system. A shelf controller (3) interrogates each card on every read or write operation to determine the card type and effects a comparison between the card identity and the configuration map. Any hardware configuration error results in an output error message which may specify the error down to card level. Thus system configuration errors are automatically identified using a relatively inexpensive hardware modification of standard circuit cards. <IMAGE>

Description

APPARATUS FOR CHECKING A SYSTEM CONFIGURATION The present invention relates to apparatus for checking a system configuration and more particularly but not exclusively to such apparatus for checking the configuration of a system comprising a multiplicity of electronic circuit cards.

Complex electronic systems such as telecommunications switching systems may comprise a very large number of circuit cards. Such cards may be "plug-in" modules housed in shelves of racks. The cards are often similar in appearance and, for standardisation, my be interchangeable between 'slots' of the shelves The overall configuration of cards, that is their positions relative to one another may vary from system to system. This results from the requirements of the system to function in a particular manner in one application and in a different manner in another application resulting in a differing "mix" of standard cards, rack interconnections being modified accordingly.

Thus it may be expected that "standard" cards will from time-to-time be inserted in an incorrect position which may lead to a system malfunction which is difficult to detect.

It is an object of the present invention to provide apparatus which monitors the configuration of an electronics system to avoid such system malfunctions.

According to the present invention there is provided apparatus for checking a system configuration in an electronic system, wherein a data store stores data defining a configuration map for the system, card identifying means scans each slot of the system to determine which type, if any, of circuit card is held therein and processor means compares the type of card so determined with the configuration map for identity such that, in the absence of such identity, the apparatus may fully specify an error.

Preferably the apparatus includes output means through which rack, shelf, card and card type may be displayed.

Such display may be on a hard copy printer and may be accompanied by an audible and/or visual alarm.

Apparatus in accordance with the invention will now be described by way of example only with reference to the accompanying drawings of which: Figure 1 shows a block diagram form a system including apparatus in accordance with the invention; and Figure 2 shows a block diagram of an identity checking arrangement for the system of figure 1.

In the United Kingdom telephone exchange system known as System 'X' , time division multiplexed digital switching is employed. The assignee of the present invention has devised apparatus for monitoring the integrity of the digital network which apparatus may cause modification of switching patterns to avoid digital routes which fail to provide adequate service.

The aforementioned equipment is referred to hereinafter as "ASDSPN" standing for "Automatically Switched Digital Service Protection Network".

The function per se of either System X or ASDSPN is not further discussed herein since neither is relevant to the invention save to serve as an example of systems comprising racks of equipment comprising a large number of printed circuit cards which slide into shelves. The cards are interconnected by shelf and rack wiring on multi-pin sockets into which they are plugged.

Referring now to figure 1 an ASDSPN terminal station is made up of a number of racks, 1, of equipment. Each rack 1 is divided into a number of shelves 2 each of which has a control unit 3 and a number of plug-in cards defining shelf functions 4. The cards 4 communicate with their respective control units 3 by way of a parallel data bus 5.

The ASDSPN terminal station also comprises central equipment which includes a processor 7 (for example a Hewlett Packard (Trademark) No1000 minicomputer). The processor 7 has links to an alarm system 8, display units 9 and a hard copy printer 10.

Communication between the processor 7 and the shelves 2 is by way of serial data links 11 which loop to each shelf on a rack, there being one link 11 for each rack 1.

The present invention provides each shelf 2 with a unique four-bit identity code determined by printed or connected wiring on the rack 1 backplane. This identity code appears at a dedicated position (port) of the shelf control unit 3 enabling the controller to check its shelf identity. The use of the shelf identity is described hereinafter.

The next identity check is that of the individual cards 4. Each type of card is allocated a four bit identity code which is returned each time the card is accessed on a "read" or "write" operation. The shelf controller 3 may check the returned code each time an operation is performed but will in any event check the returned code at least once per second. For the avoidance of doubt it is emphasised that the shelf code is pre-allocated and fixed during manufacture on a card type basis. Thus cards of the same type are fully interchangeable.

Thus referring to Figure 2, each card 4 includes four open collector gates 12 - 15 connected to a card identity bus 16. When the shelf controller 3 forwards an addressing signal by way of a standard address decoder 17 and a board select bus 18, providing a card enable signal through an open collector gate 19, the pulse reflects through the ones of the gates 12 - 15 which are connected to the board select signal. Those gates 12 - 15 not so connected are connected to a fixed control voltage to hold to a binary one.

Thus, as shown in figure 2, when a board select signal is present, that is on a read or write operation, the signal reflects through gates 12,14 and 15 whilst gate 13 is held high. Thus the returned identity will be "0100".

It will be appreciated that if no card 4 is present in the addressed slot, the board select signal from the bus 18 will not be reflected and the returned card identity will be "1111" on the bus 16. It will be noted that the buses 16 and 18 form part of the parallel bus 5 of figure 1.

Having described the provision of a simple, inexpensive method of modifying any plug-in circuit card to provide an identity, it is now necessary to consider the actual configuration checking arrangement. However before considering same, it is here noted that more (or less) than four identity bits may be provisioned in a system in accordance with the invention dependant upon the number of card types which may require identification.

Referring now to both figures 1 and 2, data defining the system configuration is loaded in a data base of the processor 7 as part of the programming of the system prior to its coming into service. The data base may be updated to reflect configuration changes as and when necessary by the usual methods for effecting such updates.

On initialisation of the system (ie. bringing the system into operation), the processor 7 causes data defining each shelf configuration from the stored map to be downloaded by way of the data links 11 to each shelf controller 3. If one of the shelf controllers 3 is missing, its absence is identified at this stage as no acknowledgement signal is returned. Such an absence results in a message display to maintenance staff on either or both the printer 10 or the visual display units 9.

Assuming that the shelf controller 3 is present the downloaded data is transferred to random access memory of a microprocessor 21 by way of an internal bus 22. The microprocessor 21 now causes shelf initialisation, that is to say each position on the shelf is sent a board select signal in turn to force return of a card type identity on the card identity bus 16. A comparison between the returned identity which is temporarily stored in an identity register 20 and the expected identity from the microprocessor 21 RAM is carried out by the microprocessor and any discrepancy causes the return of an error message to the central hardware 6 for display and or printing.

The message forwarded identifies the shelf, shelf position and card type present (or a "card out" report) as appropriate. It will also be noted that the presence of a card in a shelf position which is spare will also cause an error report to be generated.

It is here noted that the read and write operations used for initialisation are, in practice, part of a setting up procedure involving the provision of various parameters to the cards 4. The configuration check accordingly does not require any specific departure from normal initiatisation procedures.

Once initialisation has been completed and the system is running checking of card types proceeds as previously described on each read or write operation or periodic intervals. Any discrepancy between the configuration map and the actual hardware configuration is thus rapidly identified.

It will be appreciated that if a card 4 is removed from a shelf 2 and subsequ#ently replaced, the microprocessor 21 will cause two messages to be sent, the first identifying that the card has been removed and the second noting its replacement.

It will also be appreciated that the processor 7 may, on receipt of an error report, cause an audible and/or visual alarm to be raised by way of the system alarm scheme 8.

Claims (7)

1. Apparatus for checking a system configuration in an electronic system wherein a data store stores data defining a configuration map for the system, card identifying means scans each card slot of the system to determine which type, if any, of circuit card is held therein, and central processor means compares the type of card so determined with the configuration map for identity such that, in the absence of such identity, the apparatus may fully specify an error.

2. Apparatus according to claim 1 in which the system comprises racks and shelves of equipment, each shelf having a shelf controller to which data defining the shelf configuration is downloaded from the central data store, the shelf controller comprising comparison means for comparing card identity signals with the expected identity and processor means arranged to cause a message to be sent to the central processor means if non-identity is detected.

3. Apparatus according to claim 1 or claim 2 wherein the central processor includes output means for forwarding information identifying rack, shelf, card and card type for display.

4. Apparatus according to claim 3 wherein the output means is connected to a hard copy printer.

5. Apparatus according to claim 3 or claim 4 wherein the output means is connected to a visual display,

6. Apparatus according to any preceding claim wherein card identity signals are derived from a card enable signal, the card enable signal being reflected through a plurality of gates to a multi bit identity bus.

7. Apparatus for checking a system configuration substantially as hereinbefore described with reference to the accompanying drawings.