Distributed computer system arrangement

1 2

module manufacturer because the invention solves this

DISTRIBUTED COMPUTER SYSTEM problem.

ARRANGEMENT The system builder is, for example, to be able to decide whether he wants an electrically isolated contact in

The present invention relates to a distributed com- 5 the connecting device or not without assistance from

puter system arrangement with master units and slave the module manufacturer. He can choose between opti

units which communicate with one another via a serial cal and/or electrical transfer media. The latter will in

bus connection and in which the slave units can be turn need not consider the question of whether or not

connected to the connection via connecting devices and there is to be an electrical contact in the connecting

on their respective connection can be assigned identifi- 10 device.

cations in the system. What can be considered to be characteristic of the

Systems with parallel-connected multiprocessors new arrangement is that the identification of the module

which operate in real time are already known. As an ""its in the system can be effected by means of memory

example of such a system, the TRAINET system can be members and/or microprocessor members which are

mentioned, which is offered on the open market by 15 arranged in each control device or associated each con

KVASER, Kinna, Sweden. Another system is consti- tro1 device. As an alternative or complement to a micro

tuted by the CAN system which operates with priori- processor, an advanced logic circuit can be used. In one

tised messages. Through the former system, it is already embodiment information in, the memory member and

known to arrange module units which can be connected (0T microprocessor member can be read out or accessed

to the bus connections) in question. For establishing 20 from elther the connected module umt or the bus con

the identification of each connected module unit, use nectlon' °r both module ^ the bus fonnec

has thus far been made of mechanical switches (DIP tlon-In the casf where a microprocessor member is in

switches) or binary codes which have been arranged in °ne or more of ^ connecting devices, the master m

or at the connecting devices. By adjustment of said the ... cTM c°mmumcate with the processors of the

switches or introduction of said binary codes, a higher- 25 ?0lmefmS deTMeS ... P^TM^^11TM^

level unit (master unit) in the system can assign^ the *°n staf» which are intended for this. Alternatively,

„ , , , , . .v , ~. the master may communicate during communication

connected module a number in the loop connection m . ,. ,J.. , . ° ..

r stages m which the bus connection/connections are not

—» '• , . it_ .j. occupied by other, ordinary communication. As an

There is, however, a requirement that the system can 3Q ^ ^ connector processors can be t0

be given a structure which makes possible a categonsa- ... ^ emer c st messages t0 a unit m

tion from the point of view of the designer. Systems of ^ uter tem via the bus connection. Connect

this type are relatively complex and there is a marked ^ devices can be of different designs> ^ or

requirement to separate, for example, the work of the electrical connection between connecting device ele

system builder from the work of the module manufac- 35 mgnts fa connecting devices. In one embodiment, each

turer. Intimate cooperation has thus far been necessary connecting device has relatively few connecting mem

between said two categones, which has, for example, bers/conductor connections. In one embodiment, use is

meant that the module manufacturer has had to have made 0f two bus connections in the system, the first bus

great knowledge of the communication system as such. connection of which is used for basic information in the

The system builder has in turn been compelled to go 40 system and the second bus connection for giving com

into detailed designs which can be related to the struc- rnands and for reporting messages (trigger signals and

ture of the module units. There is thus a requirement to /or sync ... One and the same connecting device

arrange an interface/a barrier between the communica- can nave connections or connection conductors to two

tion functions and the module functions. different bus connections, to two pairs of connection

SUMMARY OF THE INVENTION 45 conductors from a bus connection, power supply, emergency stop function and identification. In one embodi

The aim of the present invention is inter alia to solve ment, use is made of relatively few connecting mem

this problem. bers/conductor connections, for example 9.

It is possible to carry out the arrangement of an inter- The invention also takes into consideration systemface or a barrier so that the computer system is capable 50 specific structural parts as emerges from the following of accomplishing its tasks and functioning without inter- patent claims.

ference from the barrier. It is thus possible, for example, The advantages of the invention become apparent. A for the higher-level unit (the master) to reconfigure the natural barrier can be arranged in each connecting dewhole system with the aid of software changes. It is also vice between the system builder and the module manupossible, for example, to carry out the numbering and- 55 facturer. Standard connectors with an interface can be /or renumbering of the modules in a simple manner by produced in long production runs which brings down means of digital communication with the invention. As the costs of connecting devices. Connecting devices can far as connecting functions in systems of this type are be made with a few connecting conductors, which simconcerned, it is a generally known fact that the costs for plifies the connecting device structure and thus makes such connectors are high. It is therefore of important to 60 the same less expensive. A connecting device can be bring down the number of connecting conductors in the made in different versions, for example with or without connecting device which the invention also provides. It electrical isolation. It is to be noted in this connection is of interest as far as the builder of the module units is that the electrical barrier constitutes a costly part for concerned to be able to make long production runs with the module unit as such, while it is only a small part for a few model versions. The module manufacturer is able 65 the system part. With increasing frequencies, electrical to build bis modules starting from performance informa- isolation becomes more expensive. By means of the tion from the system builder. The system builder is in invention, different designer categories can operate in turn able to build the system without assistance from the parallel without mutual influence. The only thing that 3 4

the module builder needs to know is what performance regard to competition which gives a price/performance

the module unit is capable of carrying out and this can solution which is best for him without losing the possi

be indicated by the system designer at an early stage. By bility of standardised connection of modules to the

means of the invention, it becomes possible to imple- system. According to the invention, the physical stock

ment more sophisticated solutions for the bus connec- 5 ^ reieased from the different modules at the same time

tion as such than has previously been possible. The ^ simple structural possibilities for the communication

module builder can work with minimised knowledge of line are brought about m a simple manner. The parts

the system. In a case with a microprocessor in the con- which ^ ^ ^ for the hysical stock like

necting device, a special time/time interval can be as- t lers ^ drive electronics can consequently be

signed for the communications between the higher- 10 , f . , . . ... , , ,

t i v c ^ J J.-L. ^ j • placed outside the electronics in the node/the module

level unit of the system and the connecting device pro- r T , ^ , x,. „ . , ,

TM J.- J unit. In order to do this, a T-coupler/connectine device

cessors. The connecting device processors can more- , , , , ,

over transmit emergency stop signals, which increases 18 ^duced, which links the node and the commumca

the possibilities for the system as such. It is possible to tl0n hne- In such a manner, two standardised barriers

construct simple interfaces and the CAN structure can 15 can be obtained, one for the interface between the node

likewise be preserved intact. Mechanical switches and ^the T-coupler and one for the interface between the

binary code arrangements can be eliminated in connect- T-coupler and the communication line. It is also possi

ing devices. A memory member can be used in connect- ble to handle fast signals for synchronisation. The fast

ing devices which can contain further information, for signals can be assigned to a separate bus connection,

example information on how the bus connection looks, 20 This also makes it possible to have separate bus connec

different variables/parameters which apply to the bus tions for different types of equipment and at the same

connection, the current degree of interference sensitiv- time that the machine in question can be synchronised

ity, the length of the bus connection and so forth. by means of this common synchronisation communica

LIST OF FIGURES t'on' *n on*er *^at ^e connected n°de know its place in

25 the CAN communication, there should be information

An embodiment of an arrangement which shows the about its place in the system. In order to obtain full or characteristics which are significant for the invention is g00(j flexibility, there should also be information on described below with simultaneous reference to the how the transmission of bits is to take place. According attached drawings, in which: to &e invention, it can be specified how this informa

FIG. 1 shows in block diagram form a computer 30 tion is transferred to the node on connection to the system with master units and slave umts connectedvia communication line/bus connection. According to a bus connection and connecting devices (T-boxes), FIQS ^ a 9 m DSUB connector ^ sockets is to

FIG. 2 shows m diagrammatic form a wiring diagram fee for tQ ^ T-coupler/connecting

for a connecting device to a module unit, , T ... .. , . r . ,

_,T/_, ^j-r ^ c-.c device. In this connecting device, the pins have the

FIG. 3 shows a connecting device for connection of 35 . . e v

the master unit, which connecting device includes a g n.

power supply for the bus connection,

FIG. 4 shows in diagrammatic form a connecting Pul Function

device with built-in microprocessor instead of a mem- : „, , ,—~.—; :—:—~~Z

, j. TM„„ < j ,n 1 +5 Volts for driving electronics in the T

ory member according to FIGS. 1-3, and 40 coupler> ^ +150 ^

FIG. 5 shows in perspective the connection of a mod- 2 GND for + 5 Volts, on pin l.

ule unit to machinery and to a connecting device for 3 CANout, transmission on the CAN bus, high when connection to the bus connection. recessive.

An arrangement implementing the invention can be 4 CANin' «cePti°n from the CAN bus, high when

based on a hardware connection with a 9-pin DSUB 45 s gYNCout, transmission on the CAN bus for connector. Via this connector, signals are transmitted synchronisation, high when recessive,

for a CAN bus, a synchronisation bus, an emergency 6 SYNCin, reception from the CAN bus for synchrostop bus, a serial input of address and bus data, as well nisation, high when recessive,

as power supply to external electronics. The signals can 7 EMERGENCYout, a signal for driving the emer

be held at TTT level and a nower <ainr.lv is effected 50 genoy stop Une'low on emer8ency stoP

oe aeia at 11 Ljevei ana a power supply is enectea g cODEdata, serial data, with address and mode

with + 5 Volts. The signals are transmitted to a T-cou- for speciflcatjon on interpreting data

pier which can contain electrical isolation of different see section 4.2.

types as well as drive electronics for driving signals On 9 EMERGENCYin, a signal which reflects the level

the communication line. How the communication line is on emergency stop bus, low on emergency

constructed depends upon which requirements are 55 stop Preset of the modme this used for

r . c. ,. i clocking m data on the line CODEdata.

made of the communication lme m terms of electrical

isolation, voltage levels, type of line, transmission

lengths and transmission rate. Although this part can Signals are to follow the TTL standard on signal levels

have a different structure in different systems, an exem- except on pins 8 and 9 which have the following data, plary embodiment according to the following is pro- 60

posed. In the computer system (the CAN system), com- '■

munication circuits of the type INTEL 82526 and ! XlTM < y.oits, vhigh > 3.85 Volts.

. , , . 9 Vlow < 1.35 Volts, Vhigh > 3.85 Volts.

82C200 (Philips) can be used. Other components can

nevertheless be used in this connection. It is also possible to group different functions in separate loops with 65 The information in question is entered into a memory

CAN communication, retaining the possibility of syn- circuit of the type X24C01 from XICOR or equivalent,

chronising the entire system with another CAN com- As a proposal, the following information can be in

munication. The system builder can use a solution with eluded in said memory circuit/memory member.