DE2823708A1 - TDM data transmission with bus system - involves short-circuit detectors in bus line with switches for disconnection of its sections - Google Patents

Abstract

The bus system (100) has a bus line with subscribers connected to it, which can be connected to each other in a predetermined order and specified combinations. Each subscriber has at least one programmable counter whose counting input is connected to a clock pulse generator, and output to switches making a connection between the bus line and a data source or drain of this subscriber. All subscriber counters are synchronized with each other, as in 2750818. In order to protect the bus line, switches are provided for detection of short-circuits and for disconnection of the line individual sections.

Description

Arrangement for time-division multiplex data transmission

with a bus system The invention relates to an arrangement for time division multiplexing Data transmission with a bus system that has one bus line and several to the bus line Affiliated participants includes who in a predetermined sequence in a predetermined Combination with each other in a data-transferring connection, in which preferably each participant has at least one programmable counter whose counting input is connected to a clock and its output with switching means for Establishing a data transmission connection between the bus line and a Data source or --- sink this subscriber is connected, with the counter All participants are synchronized with each other, according to patent. . . (Patent application P 27 50 818.5-31 In known serial bus systems, one bus line, which may include a data line and a power line, data in a predetermined Sequence to be transmitted between specified participants. although all participants connected to the bus line are always ready to receive only one participant or a specific group of participants each sent Record data for further processing.

To select this participant or a specific group of participants an address signal is sent out according to the prior art, which only the desired other participants or the desired other group of participants the information can be transferred for further processing in this participant. The end of this Transmission will indicated by an end signal on the bus line, which the next participant or the next group of participants to send their information with the preceding address signal and the following end signal.

Such known arrangements for serial or time division multiplexing Data transmission can be used to transmit analog signals and / or so-called discrete signals, which only contain yes / no information.

In order to improve the relative time in such bus systems, in which the bus system is available for the transmission of the information that can actually be used is in proportion to the total duration of the transmission that the transmission which includes address signals and end signals, according to patent. . . (Patent application P 2? 5 (1 818.5-31) it has been suggested that every participant should have at least has a programmable counter that starts at a programmed number Emits control signal and which, after reaching a predetermined, for all counters resets the same counting capacity to zero that a counting input of the counter with a clock is connected that a first control output of the counter with Switching means for establishing the data-transmitting connection between the bus line and a data source or sink of this participant and that the counters of all participants are synchronized with one another.

According to the above-mentioned patent, a measure is also taken against that even in the event of a short circuit in one or more transmission output stages of the participants Sufficient signal swing arises on the bus line, that of the acting as a receiver Participants can be evaluated.

For this purpose, the send output stages of the participants are via 3e a resistor connected to the bus line.

According to this proposal, however, the bus system is only special Short-circuit cases, namely in the event of a short-circuit in the transmission output stages against one Collapse protected.

The present invention is based on the object in a further development the arrangement proposed according to the cited patent is an arrangement for time-division multiplexing To create data transmission with a bus system, which in a wider scope is safely protected against short circuits, so that when a short circuit occurs the entire bus system does not collapse.

According to the invention, this object is based on an arrangement for time-division multiplex data transmission with a bus system of the type mentioned at the beginning This generic type is achieved in that means for detecting in order to protect the bus line of short circuits and for shutting down individual sections of the bus line are.

In this way, the line sections that themselves are disturbed by a short circuit or that are connected to participants in where a short circuit occurs at any point, decoupled from the bus system so that the rest of the bus system remains functional. It only the section of the bus line with the connected participant is functional, in which a fault, a short circuit, occurs.

A particularly useful, because simple., Realization of the facility to protect the bus line is that between the bus line and a Participants a resistor for short-circuit limitation is arranged.

Can be carried out in a similar way and also with little effort is the device with the feature that between two sections of the bus line a resistor for short-circuit limitation is arranged, marked.

In both cases mentioned above, the resistor is used to limit the current as a protective resistor in the event of a short circuit, with an extensive decoupling of the short-circuited participant or the short-circuited sections of the bus line occurs automatically because the short circuit automatically has a higher short circuit current and thus causing a voltage drop in the resistor.

This reduces the level of the signals on the data line, however the rest of the bus system is still fully functional as long as there are not too many short circuits enter at the same time.

The resistance to the shutdown or decoupling of the disturbed Participant or the disturbed section of the bus line can result in a Variant can expediently be designed as a discrete resistor. In this case it remains the structure of the bus system, in particular the bus line, is practically unchanged and is only extended with the discrete resistor at the specified point.

In a second variant, however, individual ones can also be used in an expedient manner Sections of the bus line itself consist of resistance wire. In this case not necessary the connection of discrete resistors, as in the sections of the bus line itself the voltage drops for decoupling the disturbed sections or participants in the Short-circuit occur.

In an expedient development, the resistance a have increasing resistance with increasing current.

This measure can advantageously reduce the short-circuit current can be reduced so that the sending participants are not heavily burdened. However, this development can have the disadvantage that the minimal permissible signal level on the bus line, namely on the data line, is reached sooner is than with resistors with constant resistance value and that a short circuit to a power line of the bus line may not be fused can.

With a star-shaped structure connected to the bus line Line sections with which participants are connected, it is recommended that the Resistors to be arranged near the star point.

A particularly advantageous embodiment of the invention with the features that to protect the bus line means for detecting short circuits and for Individual sections of the bus line are intended to be shut down, has the following characteristics: that a level sensor for detecting level fluctuations on a data line the bus line is connected to the bus system as a participant and that everyone Line section to be shut down via an overcurrent switch each configured as a subscriber with a control circuit arrangement centrally through the level sensor in any Dsten transmission cycle can be switched off and according to one of the level sensor in a switch-on command sent out in a subsequent data transmission cycle as well as in the control circuit arrangement of evaluated electrical quantities of the respective Line section can be switched on.

This arrangement is particularly advantageous in a bus system that a protected trunk system with participants that cannot be switched off and proportionately Has crash-endangered further line sections. The level sensor for detection of level fluctuations is advantageous in this case in the trunk system to the data line connected to the bus line. Both the level sensor and the overcurrent switch are in the present case participants of the bus system in which data in consecutive Data transmission cycles are transmitted.

In the event that a change in level exceeds a predefined permissible Level is determined by the level sensor, all overcurrent disconnectors are immediately activated by preferential command transmission to switch off the assigned line sections caused.

This happens regardless of whether the respective line section, which can be switched off by the Uberstromabscnalter, is disturbed or not. By doing The level sensor issues a switch-on command in the following data transmission cycle to all overcurrent disconnectors, as it determines the signal level of the bus line in the trunk system recognizes as being free of interference. However, only those overcurrent disconnectors switch again the associated line sections, which in accordance with the control circuitry of the overcurrent switch-off of evaluated electrical variables, which provide information about there is a short circuit in the respective line section, this line section back on.

By switching off all crash-prone line sections the line section with data interference is also recorded with certainty. With the trunk system of the bus system coupled participants, Gle does not have an overcurrent switch are connected, remain in function. The overcurrent breakers, which the Securing participants to the trunk system can use both short-circuited meshes and also uncouple strands from the trunk system. For a stitch that has two ends attached to the Bus system is connected, there is an overcurrent switch at each end of the mesh needed, while for a strand that is only connected to the bus system at one end only an overcurrent switch is required.

This backup system largely eliminates the effects of Short circuits on the data line of the bus line, since only the participants fail that are connected to short-circuited line sections. Any number, too Short circuits in the disconnectable line sections do not lead to the failure of the entire bus system. The signal voltage levels on the rest of the bus system will be not influenced by short circuits in any line sections that can be switched off. Above all, all participants in the signal bus system can be specially protected must be, like the level sensor, a participant for a steering aid and a participant for a pre-brake, remaining fully functional in the trunk system.

A preferred embodiment of the above arrangement is with equipped with the features that in the overcurrent breaker a control circuit arrangement to measure the resistance between the data line and a ground line to form a control signal is provided and that the control signal and the switch-on command to a switch-on signal that can be switched on the line section in a logic system circuit arrangement is linkable.

In an advantageous manner, a switch-on signal is only then used Switching on an output given a level fluctuation detected by the level sensor, when this level sensor issues a switch-on command again and when the control circuitry by measuring the resistance in the disconnectable line section has not detected a short circuit. So a short to ground becomes a switching decision of the overcurrent switch.

In a particularly expedient development of the arrangement, it is provided that that the control circuit arrangement of the overcurrent switch in addition to the evaluation the polarity of the voltage on the data line of the line section that passes through the overcurrent switch can be switched off, with respect to a power line and to Generation of a control signal is designed as a function of the polarity, that with the switch-on command of the level sensor in the logic circuit arrangement Formation of a switch-on signal can be linked.

This development makes use of the fact that the signal voltage level on the data line of the bus line normally always is less than the positive battery potential that is on a power line of the Bus line prevails. The polarity of the voltage between the data line and the Power conduction to the overcurrent breaker is a criterion for one in this case Short circuit to the power line and leads through logical linkage of the The switch-on command issued by the level sensor also leads to a switching decision of the Overcurrent switch. Only if the voltage has a polarity that is normal Indicates the operating status, a switch-on signal is sent to the switch of the overcurrent switch submitted.

In the event of a short circuit to ground, the voltage between the data line has and the power line a reverse Polarity, and in this The case is, as described above, the resistance between the data line to ground to form the switching decision in connection with the output from the level sensor Switch-on command evaluated. The control circuit arrangement with the means for evaluation the polarity also allows short circuits in the data line to be detected to the power supply line and to a fuse for the bus system in the event of a fault.

In an advantageous manner, the power line itself can through the Overcurrent disconnectors are protected by a switching contact in the power line is arranged, which can be actuated by the switch-on signal. With the triggering of the In this case, the short-circuit protection by the overcurrent disconnector is also the Power supply to the subscriber of the disconnected line section interrupted. The participant is expediently set up in such a way that he can, in the event of a lack of energy goes to the off position.

In detail, the arrangement which disconnects the system is disturbed Line sections enabled in the aforementioned malfunctions, expedient designed with the features that in the overcurrent breaker a switch in each the power line and the data line is arranged that a connection from a connection of the switch that is connected to the energy source leads in the power line to the control circuit arrangement and that each one connection from one connection with the level sensor and one with the connection of the switch connected to the disconnectable line section leads in the data line to the control circuitry.

This means that this arrangement can also be used in the event of a short circuit in the power line Mass remains functional, it is furthermore expediently characterized by a Fuse in the power line on the side connected to the power source of the overcurrent switch.

The invention is explained below with reference to a drawing with three figures described. It shows: FIG. 1 an arrangement for partial protection with resistors, 2 shows an arrangement for the partial protection of particularly endangered participants with overcurrent cut-off device and a level sensor and FIG. 3 shows an arrangement of an overcurrent cut-off switch in a bus line.

In Fig. 1 1 to 5 participants of a bus system are designated, which are arranged in crash-prone zones.

Each participant 1, 2, 3 and participants 4 and 5 are common via one line section 6, 7, 8, 9 of a bus line to one in one not Central bus line 10 arranged in a crash-prone fuselage system is connected.

Between the common connection point 11 and the line section 6 or between the connection point 11 and the line section 7 is close of the connection point each a resistor 13 or 14 is arranged. The same is between the central connection point 12 and the line section 8 a resistor 15 and A resistor 16 is arranged between the connection point 12 and the line section 9. Each resistor is connected near the connection point, making a as large a part as possible of the line sections 6, 7, 8, 9 in the event of a short circuit are recorded.

If there is a short to ground in the line section at a point 17 6, a voltage drop occurs across resistor 13 that is approximately the same the voltage prevailing on the central bus line 10.

The short-circuit current caused by the short-circuit to ground at point 17 is limited by the resistor 13, so that the voltage level is on the central bus line 10 drops, but not so deep that the participants 2, 3, 4, 5 would no longer be functional. So only participant 1 inoperable. In particular, participants not shown in the drawing, which are directly connected to the central bus line 10 in this way functional rubbing.

The entire bus system shown in Fig. 1 can then also at lower Voltage levels on the bus line 10 work if still on a second or further point 18, 19, 20 of a possible ground short circuit, such a ground short circuit entry.

In Fig. 1 with the interrupted drawn resistors 21, 22 indicated that the central bus line 10 in itself by current-limiting Resistances can be fused in sections.

Instead of the discrete resistors shown in FIG individual conductor sections can also be made from resistance wire.

The line shown schematically in FIG. 1 is the data line of the bus system.

The bus system according to FIG. 2 largely corresponds to the little Fig. 1 with the participants 1, 2, 3, 4, 5, who via line sections 6, 7, 8, 9. are connected to a central bus line 10. In addition, in Fig. 1 is still a subscriber 23 with the line section 8 in connection, further is another Subscriber 24 connected directly to the central bus line 10. Of the participants 24 and the central bus line 10 are located in a crash-protected fuselage system 25, which is indicated by a dash-dotted line.

The line sections 6, 7, 8, 9 are instead of / resistors over Overcurrent disconnectors 26, 27, 28, 29 coupled to the central bus line 10. These Overcurrent disconnectors form participants in the bus system. Within the trunk system 25 a level sensor 30 is also connected to the central bus line 10; even the level sensor is a participant in the bus system.

The crash-prone line sections, drawn with thick lines 6, 7, 8, 9 are secured to the trunk system via the overcurrent disconnectors. The protection takes place in such a way that all overcurrent disconnectors have their associated Switch off line sections from the trunk system when the signal level is on the central Bus line 10 drops below a specified minimum value - in the extreme case of a short circuit - what is detected by the level sensor. The level sensor switches off immediately the line sections issue a shutdown command with preferential command transmission.

Generated in the data transfer cycle following the shutdown the level sensor gives a switch-on command, but only to switch on the people disconnected line sections that are not disturbed or short-circuited are. For this purpose, in addition to the switch-on command, the electrical Sizes of the associated switched-off line sections, namely the resistance of the data line with respect to a ground line and the polarity the voltage on the data line to a power line is evaluated and with the Switch-on command linked. Only the undisturbed line sections are then used switched on again, while the disturbed line sections remain switched off and while the central trunk system with the level sensor 30 and the participant 24 always remains in operation.

An arrangement of an overcurrent switch in one of a data line 31, a ground line 32 and a power line 33 existing bus line shown in Fig. 3. The overcurrent breaker 34 is within a dash-dotted line Line shown. It comprises a control circuit arrangement 35 with a logic circuit arrangement, as well as a switch 3E in the data line and a switch 37 in the power line, which is connected to a battery (not shown) on the left.

On the left in Fig. 3 there is also the one not shown central bus line from which the data line 31 is branched off.

To transmit the switch-on command to the control circuit arrangement this is connected to a connection 38 with the level sensor connected to the data line. To evaluate the electrical parameters aes to be switched off and on Line section on the right in Fig. 1 represents 1e control circuitry with a connection 39 on the data line of the disconnectable line section in Link. There is also a connection between the control circuitry and a connection 40 to the power line 33 on the battery facing Switch side 37.

In the event of a short circuit of the data line 31 to the ground line 32 or the control circuit arrangement receives the power line 33 via the data line 31 from the level sensor a switch-off command that the opening of the previously closed Switch 36 and 37 initiated.

When a switch-on command occurs in the subsequent data transmission cycle The control circuit arrangement closes via the data line 31 and the connection 38 does not automatically switch 36 and 37, but first evaluates the electrical ones Sizes of the switched off line section. To do this, the resistance between the connection 39 and a connection a on the ground line evaluated, the only when a certain resistance value is exceeded, a control signal to switch it on again in connection with the switch-on command. In addition, the condition is used that in undisturbed operation the potential on the power line is always positive than the potential on the data line. will be such a tension between the Terminal 40 and the data line are not detected, so forms the control circuitry no control signal that is connected to the switch-on command that is connected to the control signal is linked in a logic connection, a switch-on signal for the switch 36 and 37 forms. The control circuit arrangement must therefore not cause any disturbance a short circuit to the ground line nor to the power line to detect the disconnected Turn on line section player. -M difference to the arrangement according to Fig. 1, with the arrangement according to FIG. 3, the power line is also protected against short circuits, in that it can be switched off with the switch 37. Should a fuse 42 in the Z¼nergieleitung be arranged for further protection, this fuse is between the overcurrent switch 34 and to arrange the battery, not shown, so that the overcurrent switch remains functional even in the event of a short circuit in the power line to ground.

Claims (9)

Claims arrangement for time-division multiplexed data transmission with a bus system that has one bus line and several connected to the bus line Participants comprising who in a predetermined sequence in a predetermined combination are in data-transmitting connection with each other, preferably in which each participant has at least one programmable counter, the number input with a Clock is connected and its output with switching means for production a data-transmitting connection between the bus line and a data source or lower this subscriber is in communication, the counters of all Participants are synchronized with each other, na & n ratent (patent application P 27 50 818.5-31 characterized in that means to secure the bus line Detection of short circuits and to shut down individual sections of the bus line are provided. 2. Arrangement according to claim 1, characterized in that between the bus line (central bus line 10) and a participant (1, 2, 3, 4, 5) Resistor (13, 14, 15, 16) is arranged to limit the short circuit. 3. Arrangement according to claim 1, characterized in that between a resistor (21, 22) is connected to limit the short circuit 4. Arrangement according to claim 2, characterized in that the resistor (13, 14, 15, 16, 21, 22) is more discrete Resistance is formed. 5. Arrangement according to claim 2, characterized in that individual Sections of the bus line consist of resistance wire. 6. Arrangement according to one of claims 2 to 5, characterized in that that the resistor has a resistance value that increases with increasing current. 7. Arrangement according to claim 1, characterized in that a level sensor (30) for detecting level fluctuations on a data line (31 in FIG. 3) of the Bus line (central bus line 10) connected to the bus system as a participant and that each line section (6, 7, 8, 9) to be shut down has one each as Participants trained upstream disconnector (26, 27, 28, 29) with a control circuit arrangement Can be switched off centrally by the level sensor in any data transmission cycle and in accordance with one of the level sensor in a subsequent data transfer cycle sent switch-on command as well as evaluated in the control circuit electrical variables of the respective line section (6, 7, 8, 9) can be switched on is. 8. Arrangement according to claim 7, characterized in that in the Overcurrent disconnector (34), a control circuit arrangement (35) for measuring resistance between the data line (31) and a ground line (32) for forming a control signal is provided and that the control signal and the switch-on command to one of the Line section activating switch-on signal in logic circuitry is linkable. 9. Arrangement according to claim 8, characterized. that the control circuit arrangement (35) of the overcurrent switch (34) in addition to evaluating the polarity of the voltage on the data line (31) of the line section, which can be switched off by the overcurrent switch, with respect to a power line for generating a control signal depending on the polarity is formed, which with the switch-on command of the level sensor (30) for formation a switch-on signal can be linked in the logic circuit arrangement. 1C. Arrangement according to Claims 8 and 9, characterized in that in the overcurrent switch (3a) each a switch (36, 37) in the power line (33) and is arranged in the data line (31) that a connection from one to the connection (40) of the switch (37) connected to the energy source in the Power line leads to the control circuit arrangement (35) and that one connection each from a connection (38) connected to the level sensor and a with the disconnectable line section in connection (39) of the Switch (36) in the data line leads to the control circuit arrangement. 11. Arrangement according to one of claims 7 to 10, characterized by a fuse (42) in the nergleleitung (33) on the one connected to the power source Side of the overcurrent switch (34).