GB2263049A

GB2263049A - Control system controlling moving faders

Info

Publication number: GB2263049A
Application number: GB9226132A
Authority: GB
Inventors: Noboru Ishihara
Original assignee: Teac Corp
Current assignee: Teac Corp
Priority date: 1991-12-20
Filing date: 1992-12-15
Publication date: 1993-07-07
Anticipated expiration: 2012-12-15
Also published as: GB9226132D0; GB2263049B; JPH05176399A; DE4243124A1

Description

2263049 1 CONTROL SYSTEM FQR CONTROLLING PLURALITY-QF PREDETERMINED

ACTIONS IN PARALLEL WITH SIMPLE CONFIGURATION The present invention relates to a control system by which a predetermined plurality of actions are controlled in parallel.

A so-called moving fader is currently used acting as a so-called mixer. The mixer (sound mixing apparatus) is used for a public address system (socalled PA system, that is, in general, a sound amplifier in which a plurality of input sounds are processed simultaneously in parallel), for recording music tunes and for processing other sounds. The moving fader has especially added and advanced functions. In the moving fader, the position of a socalled fader (general level controller) is controlled by means of a motor controlled by an automatic controlling means such as a microcomputer. The fader is a part of an input-channel-process device employed by the moving fader.

Particularly, the so-called MIDI mixer (MIDI is an abbreviation of "Musical Instrument Digital Interface", the data transferring standard for transferring playing information of synthesizers, rhythm machine (or drum machines), sequencers, computers, and similar devices, between each other; devices, signals, and other things relating to MIDI will have names headed by the term 'SIDI", for example, "MIDI apparatus", hereinafter) is currently known. The MIDI mixer controls the fader in accordance with a MIDI signal, the MIDI signal being provided from an apparatus higher in a hierarchy (this hierarchy is such that an apparatus higher in the hierarchy controls another apparatus (apparatuses) lower in the hierarchy by means of supplying control signals) such as a sequencer and other similar apparatuses, and the MIDI signal including information needed for controlling the position of the fader.

Particularly, the mixer, having a large processing capacity, has many input channels, the mixer thus employing many moving faders to be controlled. In the case of such a mixer, one microcomputer controlling the many moving faders results in large processing load being imposed on the microcomputer. Thus, it may be difficult for the microcomputer to control all of the moving faders at the same time. Such control method as one microcomputer controlling many moving faders thus is not appropriate for a mixer requiring a real time processing.

To solve the above-mentioned problem caused by control using a single microcomputer, the following apparatus is currently used. The apparatus employs a plurality of slave microcomputers for respectively controlling a desired number of faders. The apparatus further employs a master microcomputer for providing a respective control directive to each of the slave microcomputers, the master microcomputer executing necessary communications with an external apparatus (particularly, an apparatus higher in the hierarchy such as that handling the MIDI signals and similar apparatuses).

One example 2 of a mixer in the prior art is described below with reference to FIG.1. The MIDI signals are supplied to a master computer 110, the MIDI signals being provided from an external sequencer

1 through a MIDI cable (a cable for carrying a MIDI signal). The master computer 110 then reads information for moving the faders from the MIDI signal through a MIDI interface (an interface for communication using a MIDI signal), the MIDI signal coming through I/0 (input/output) port. The master computer 110 then provides control directives, based on the MIDI signal read, to slave computers 120, 130, 140, and 150 respectively. The slave computers 120, 130, 140 and 150 then control the respective moving faders (not shown in FIG.1), the control being based on the control directives.

As mentioned above, in the mixer 2, the combination of the master computer 110 and the plurality of slave computers 120, 130, 140 and 150 each connected to the master computer 110, enables each of the slave computers 120, 130, 140 and 150 to independently control the respective moving faders, the control being based on the corresponding control directives provided from the master computer 110. As a result, it is possible to simultaneously control, in real time, the respective sound volume of each signal of a plurality of input sound signals. Further, the processing load imposed on each of the master computer 110 and the slave-computers 120, 130, 140 and 150 can be reduced.

In the mixer in example 2, the master computer 110, via a transmission terminal Tx, supplies the control directives to the slave computers 120, 130, 140 and 150 via receiving terminals Rx, through buffers 122, 132, 142, and 152 respectively.

In the mixer 2, the master computer 110 can not recognize conditions resulting from the slave computers 120, 130, 140 and 150 respectively controlling the corresponding moving faders. That is, those conditions can not be fed back to the master computer 110. As a result, accurate control behavior cannot be obtained by the slave computers.

Another example 3 of a mixer in the prior art is described below with reference to FIG.2. The MIDI signals are supplied to a master computer 210, the MIDI signals being provided from an external sequencer through a MIDI cable. The master computer 210 then reads information for moving the faders from the MIDI signal through a MIDI interface (an interface for communication using the MIDI signal), the MIDI signals coming through 1/0 (input/output) ports. The master computer 210 then provides control directives, based on the MIDI signal read, to slave computers 220, 230, 240, and 250 respectively. The slave computers 220, 230, 240 and 250 then control the respective moving faders (not shown in FIG.2), the control being based on the control directives.

As mentioned above, in the mixer in example 3, similarly to the mixer in example 2, the combination of the master computer 210 and the plurality of slave computers 220, 230, 240 and 250 each connected to the master computer 110, enables each of the slave computers 220, 230, 240 and 250 to independently control the respective moving faders, the control being based on the corresponding control directives provided from the master computer 210. As a result, it is 30 possible to simultaneously control, in real time, the respective sound volume of each signal of a plurality of input sound signals. Further, the processing load imposed on each of the master computer 210 and the 1 slave computers 220, 230, 240 and 250 can be reduced.

In the mixer 3, data bus 260 connects the master computer 210 and the slave computers 220, 230, 240 and 250, via respective serial 1/0 (input/output) ports 225, 235, 245 and 255. The control directives from the master computer 210 are distributed for the slave computers 220, 230, 240 and 250, by being supplied to the serial 1/0 ports 225, 235, 245 and 255 respectively. Thus respective control directives are provided in parallel to respective receiving terminals Rx of the slave computers 220, 230, 240 and 250 from respective transmission terminals Tx of the serial 1/0 ports 225, 235, 245 and 255.

Further, the slave computers 220, 230, 240 and 250 respectively transmit feedback signals, indicating conditions resulting from the slave computers 220, 230, 240 and 250 controlling corresponding moving faders, via respective transmission terminals Tx, to respective receiving terminals Rx of the serial 1/0 ports 225, 235, 245 and 255. The serial 1/0 ports 225, 235, 245 and 255 then respectively provide the feedback signals to the data bus 260. The data bus then provides the feedback signals to the master computer 210 in a manner in which 25 the master computer 210 can determine which one of the feedback signals is provided from which one of the slave computers 220, 230, 240 and 250. Thus, the master computer 210 can recognize the conditions resulting from the slave computers 220, 230, 240 and 30 250 controlling the corresponding moving faders. As a result, the master computer 210 can vary the control directives appropriately correspondingly to the feedback signals so as to realize an accurate control 1 behavior.

In the mixer in example 3, the data bus 260 supplies the control directives in parallel to the serial 1/0 ports 225, 235, 245 and 255, those control directives being provided from the master computer 210 in parallel. Further, the data bus 260 supplies the feedback signals in parallel to the master computer 210, the feedback signals coming from the slave computers 220, 230, 240 and 250 respectively serially through the corresponding serial 1/0 parts 225, 235, 245 and 255. Such a data bus, being expensive, causes the mixer 3 to become expensive. Further, a condition where any one of the feedback signals from the slave computers 220, 230, 240 and 250 cannot reach the master computer 210 due to some problems may halt the master computer 210. Thus the next instruction may not be executed by the master computer 210. As a result, the control action in the mixer 3 may be obstructed.

Another example 4 of a mixer in the prior art is described below with reference to FIG.3. The MIDI signals are supplied to a master computer 310, the MIDI signals being provided from an external sequencer through a MIDI cable. The master computer 310 then reads information for moving the faders from the MIDI signal through a MIDI inte rface (an interface for communication using the MIDI signal), the MIDI signal coming through 1/0 (input/output) ports. The master computer 310 then provides control directives, based on the MIDI signal read, to slave computers 320, 330, 340, and 350 respectively. The slave computers 320, 330, 340 and 350 then control the respective moving faders (not shown in FIG.2), the control being based on the control directives.

1 As mentioned above, in the mixer in example 4, similarly to in the mixer in example 2, the combination of the master computer 310 and the plurality of slave computers 320, 330, 340 and 350 each connected to the master computer 110, enables each of the slave computers 320, 330, 340 and 350 to independently control the respective moving faders, the control being based on the corresponding control directives provided from the master computer 310. As a result, it is possible to simultaneously control, in real time, the respective sound volume of each signal of a plurality of input sound signals. Further the processing load imposed on each of the master computer 310 and the slave computers 320, 330, 340 and 350 can be reduced.

In the mixer in example 4, the transmission terminal Tx of the master computer 310 is connected to a receiving terminal Rx of the slave computer 320; a transmission terminal Tx of the slave computer 320 is connected to a receiving terminal Rx of the slave computer 330; a transmission terminal Tx of the slave computer 330 is connected to a receiving terminal Rx of the slave computer 340; a transmission terminal Tx of the slave computer 340 is connected to a receiving termi nal Rx of the slave computer 350; and a transmission terminal Tx of the slave computer 350 is connected to a receiving terminal Rx of the master computer 310.

In the mixer in example 4 having the above mentioned configuration, each of the control directives provided from the master computer 310 has an identification code for indicating a respective one of the slave computers 320, 330, 340 and 350.Each of the -8 slave computers 320, 330, 340 and 350 determines, to according the identification codes, whether or not a received control directive is directed to that slave computer. Each of the slave computers then executes a specified controlling action in accordance with the received control directive when the received control directive is determined to be directed to that slave computer. On the other hand, each of the slave computers then passes through the received control directive to the next connected slave computer when the received control directive is determined not to be directed to the slave computer who receives the control directive.

Further, in the mixer in example 4, each of the feedback signals, provided by one of the slave computers 320, 330, 340 and 350, has a respective identification code. The master computer 310 can thus determine which one of the slave computers has provided a received feedback signal.

It is possible to reduce the cost of the mixer in example 4 because the mixer in example 4 does not need a data bus such as employed by the above mentioned mixer in example 3, further, accurate control behavior can be obtained because the master computer 310 can control the slave computers 320, 330, 340 and 350 according to the feedback signals. However, a certain time lag occurs such that a second control directive provided by the master computer reaches the second slave computer (for example, 330) at a later time than the time at which a first control directive reaches the first slave computer (for example, 320) situated before the second slave computer in the communications route. That is, the transfer times of the control directives depend on the order in which the slave computers are connected starting from the master computer. This results in inadequate real time control mixer. Similarly, the tranefer times signals from the slave computers to the behavior of the of the feedback master computer also depend on the connection order. This results in degrading of the accurate control behavior obtained due to the feedback signals. Further, a certain problem occurring in any of the slave computers disables transfer of the signal from that slave computer to the next one. This results in obstruction to the control action of the mixer 4.

A general object of the present invention is to provide a control system having a relatively simple and thus cost-saving configuration, and having an accurate control behavior. A particular object of the present invention is to provide a control system being able to accurately control a plurality of actions by employing a feedback signal indicating the corresponding actual result of the actions.

According to one aspect of the present invention, there is provided a control system comprises:

a plurality of execution means for executing predetermined actions, the plurality of execution means then providing feedback signals indicating conditions resulting from the execution of the predetermined actions; control means for controlling the plurality of executing means by applying control signals thereto so as to cause the plurality of execution means to execute the predetermined actions independently from each other; and 1 feedback-signal passing means for selectively passing to the control means the feedback signals provided by the plurality of executing means, in a first predetermined order.

By the above-mentioned configuration, the feedback-signal passing means selectively passes the feedback signals respectively provided by the plurality of executing means. Thus, it is possible to easily determine which feedback signal passed by the feedback- signal passing means is provided by which one of the executing means, because only the feedback signal selected by the feedback-signal passing means only passed to the control means. That is, the feedbacksignal passing means selects the execution means from which the control means should get the feedback-signal. Further, even if the feedback signal cannot be obtained by the control means from the selected execution means, this condition will not cause obstruction to the action of the system because the feedback-signal passing means can select the other execution means.

Other objects and further features of the present invention will be apparent from the following detailed description when read in conjunction with the accompanying drawings.

FIG.1 shows a block diagram of a mixer of one example of a control system in the prior art;

FIG.2 shows a block diagram of a mixer of another example of a control system in the prior art;

FIG.3 shows a block diagram of a mixer of another example of a control system in the prior art;

FIG.4 shows a block diagram of a mixer of a first embodiment of a control system according to the present invention; FIG.5 is a table showing logic levels set by the code setting switches in slave computers of the mixer shown in FIG.4; FIG.6 shows bit assignments in a control directive provided from a master computer of the mixer shown in FIGA; FIG.7 shows one example of the bit assignments in a control directive provided from. a master computer of the mixer shown in FIGA; FIG.8 shows a block diagram of peripheral configurations for the master computer and the slave computers of the mixer shown in FIGA; FIG.9 shows a configuration of the hierarchy below the slave computer of the mixer shown in FIGA; FIG.10 shows a control flow chart of the slave computer of the mixer shown in FIGA; and FIG.11 shows a mixer of a second embodiment of the control system according to the present invention.

A mixer 1 of a first embodiment of the control system according to the present invention is described below with reference to FIG.4. A master computer 10, acting as a control means, is connected, through a MIDI interface 1Ov to an apparatus higher in the hierarchy such as a sequencer, that is, a computer providing information for playing tunes automatically.

The master computer 10 sends control directives to the below-described moving faders, according to the information for playing tunes automatically. Slave computers 20, 30, 40 and 50, each acting as executing means, respectively control the moving faders, the control being based on the control directives. The control directives pass through respective directive 1 circuits 22a, 32a, 42a and 52a between the master computer 10 and the respective slave computers 20, 30, 40 and 50. The slave computers 20, 30, 40 and 50 respectively provide feedback signals indicating conditions resulting from the respective slave computers' control of the moving faders, the feedback signals then passing through respective feedback circuits 21a, 31a, 41a and 51a so as to reach the master computer 10. Respective receiving switches 21, 31, 41 and 51, each acting as a feedback-signal passing means, are provided for each of the feedback circuits 21a, 31a, 41a and 51a. Each of the receiving switches 21, 31, 41 and 51 identically switches the respective feedback signal.

The master computer 10 comprises a CPU (central processing unit), a ROM (read only memory), a RAM (random access memory) and an 1/0 (input/output) port. The ROM has a program stored in it, the master computer 10 acting in accordance with the program. The RAM is used for storing data, the data being processed by the master computer 10. A MIDI signal (resulting from encoding information in accordance with the above mentioned MIDI standard, that information being the above mentioned information for playing tunes automatically, the signal being previously encoded) is supplied to the master computer 10 via the 1/0 port, through the above mentioned MIDI interface 10v, from the above mentioned apparatus higher in the hierarchy.

The MIDI interface 10v is connected to the master computer 10 through the 1/0 port (not shown in FIG-4). The MIDI interface 10v has three terminals respectively called "IN", "OUT" and "THRU", for electrically connecting to the external devices, as 1 13 - 1 shown in FIGA. The above mentioned MIDI signal is supplied to the "IN" terminal. The "THRT' terminal is internally connected to the "IN" terminal via photocouplers for isolating those terminals from each other, the "THRT' terminal thus isolating signals between both sides. The "THRT' terminal is used for connecting another MIDI device such as a mixer or an electric musical instrument to the apparatus higher in the hierarchy in parallel with the mixer 1.

The above-mentioned "OUV' terminal is used when, for example, a program for playing tunes automatically is produced through the mixer 1. In this case, the direction of information flow is the reverse of the normal information flow direction in which the information for playing tunes automatically flows from the apparatus higher in the hierarchy to the slave computer 20, 30, 40 and 50 through the master computer 10. In the case where the program for playing tunes automatically is produced, a player (a human being, who is a producer of the program) plays a tune by operating moving faders; the slave computers 20, 30, 40 and 50 then respectively provide signals according to the operations of the moving faders; those signals are then provided to the master computer 10; the signals is then converted into MIDI signal; and this MIDI signal is then output to an apparatus higher in the hierarchy through the "OUV' terminal of the MIDI interface 1Ov. The apparatus higher in the hierarchy, for example a personal computer, then stores the MIDI signal on a recording medium as the program for playing tunes automatically. This stored program may be used to play tunes automatically via the mixer 1. Further, an aspect of the MIDI signal such as which musical 1 instrument is assigned to each MIDI channel can be changed by means of the program by which the master computer 10 acts, the MIDI signal being output from the "OUV' terminal.

MIDI signals input at the 4bove-mentioned "IN" terminal are those for moving faders. The MIDI signal has information indicating desired tones, volumes and other elements of sound for a tune. Such information can be represented by numerical values.

Then, these numerical values are used for indicating positions of the faders so that the motions of the faders result in volumes of input (sound) signals varying. As a result, the playing of tunes automatically can be realized.

The master computer 10 produces, based on an input MIDI signal, the control directives for controlling the moving faders through the slave computers 20, 30, 40 and 50 so that the motions of the faders result in volumes of input (sound) signals varying. The control directives are output from a transmission terminal T= comprising a serial port. The master computer 10 has a receiving terminal R= for supplying the above-mentioned feedback signals thereto. Each of the slave computers 20, 30, 40 and 50_ has a respective receiving terminal Rxs. The transmission terminal T= of the master computer 10 is connected to the receiving terminals Rxs of the slave computers 20, 30, 40 and 50 through respective buffers 30 22, 32, 42 and 52. An identification code is assigned to each of slave computers 20, 30, 40 and 50. Those identification codes are set by code setting switches 1 20Z (not shown in FIG.4), 20F and 20S of the slave computer 20; 30z (not shown in FIG.4), 30F and 30S of the slave computer 30; 40Z (not shown in FIG.4), 40F and 40S of the slave computer 40; and 50Z (not shown in FIG.4), 50F and 50S of the slave computer 50. Functions of those switches are such that one state of a switch, for example, the state of the switch 20F, in which the common terminal thereof is connected to a voltage terminal Vs, results in output of a logic high "H" C'V') level; and the other state, in which the common terminal thereof is grounded, results in output of a logic low "L" ("0") level.

In the mixer 1, the above-mentioned code setting switches of the slave computers 20, 30, 40 and 50 are, for example, in the states shown in FIG.4 (the switches 20Zy 30Zy 40Z and 50z are all in the condition of the "L" logic levels output). Thus, logic levels of the code setting switches are as shown in FIG.5. Each of these logic levels of the code setting switches represent a bit in a binary number. For example, the logic levels of the switches 20Z, 20F and 20S respectively correspond to the leftmost bit, the middle bit and the rightmost bit of the identification code of the slave computer 20. The identification codes of the slave computers 20, 30, 40 and 50 are thus respectively "000", "001", "01C and "Oll". Further, the configurations of all the slave computers 20, 30, 40 and 50 are the same, with respect to both hardware and software, except for the abovementioned states of the 30 code setting switches.

The above-mentioned control directives, provided to the slave computers 20, 30, 40 and 50 from the master computer 10 are described below with 16 1 reference to FIG.6. Each of the control directives comprises a binary number of eight bits. The most significant bit (MSB) b7 indicates whether information represented by the control directive corresponds to a command or to data relating to a command. The next three bits, that is, the second through fourth significant bits %, b5 and b4 represent the abovementioned identification code assigned to each slave computer. These bits b6 through b4 can express eight values (23=8, the symbol "" expressing the mathematical operation of raising to a power, for example, 23 meaning 2 raised to the third power, hereinafter) from 0 through 7. The least significant bits b3 through bo specify the command or data for a command. These four bits b3 through bo can express sixteen values (24=16) from 0 through F in hexadecimal notation.

A concrete example of the above-mentioned control directive is described below with reference to FIG. 7. In the first control directive, a value "V' in the bit b7 indicates that the first control directive corresponds to a command. Values "001" in the bits b6 through b4 indicates that the first control directive is directed to the slave computer 30 as mentioned above. Values "101C in the bits b3 through bo represent a command such as, for example, to move the fader of the second moving fader, where, in the mixer 1, eight slave moving fader belong to each slave compute, each fader comprising a sliding resistor in which movement of a sliding contact, acting as a moving member, varies the resistance thereof.

After the above-mentioned first control directive comprising the abovementioned command 1 information, a second control directive having a data, such as mentioned above for the control directive, relating to the command indicated by the first control directive, the bit b7 Of the second control directive being thus "0", is provided from the master computer 10. In the second control directive, the remaining seven bits b6 through bo are used for indicating an target position for the above-mentioned sliding c.ontact of the fader. These seven bits b6 through bo can express 128 values (27=128), thus the target position of the sliding contact can be specified as one of 128 As mentioned above, each of the control pos., directives provided from the master computer 10 has the command information represented by a binary number, the bit b the binary number being "V' and the data 7 Of il> information regarding the command represented by another binary number, the bit b7 of the other binary number being "0".

The control directives provided from the master computer 10 are respectively supplied to the respective slave computers 20, 30, 40 and 50, through the respective buffers 22, 32, 42 and 52. Each of the slave computers 20, 30, 40 and 50 then controls the above-mentioned respective moving faders belonging to it.

Configurations peripheral to the master computer 10 and slave computers 20, 30, 40 and 50, other than the above-mentioned apparatus higher in the hierarchy, are described below with reference to FIG.8.

The above-mentioned MIDI signal is supplied to the master computer 10 from the apparatus (computer) higher in the hierarchy. the apparatus (computer) specifying the above-mentioned playing tunes to be played - 18 automatically. The master computer 10 has a key switch 10d and a rotary encoder 10b, for supplying data for specifying the playing tunes to be played automatically directly to the master computer 10. The rotary encoder 10b is a device generating pulses in response to rotation of a dial thereof, the number of the pulses corresponding to the rotation angle of the dial. The rotary encoder 10b is used for providing therefrom and/or correcting thereby various values/data. Such a function is used for a fine adjustment such as an adjustment of the timing at which a tune is to be started, u"sed for an adjustment of various operating conditions, and used for other similar uses.

Eight moving faders 23a through 23h belong to the slave computer 20; eightmoving faders 33a through 33h belong to the slave computer 30; eight moving faders 43a through 43h belong to the slave computer 40; and eight moving faders 53a through 53h belong to the slave computer 50. Further, the master computer 10 has a mute signal device 10a. The mute signal device 10a can generate a mute signal for controlling those moving faders so that silence or sound having a certain sound volume occurs immediately. Further, the master computer 10 has an indication device 10c comprising an LED (light emitting diode) and an LCD (liquid crystal display).

Each of the slave computers 20, 30, 40 and 50 has a respective one of key switches 20a, 30a, 40a and 50a. These key switches enable external direct controls of the slave computers. Further, each of the slave computers has a respective one of LEDs 20b, 30b, 40b and 50b for indicating how the slave computer acts.

A configuration of the lower hierarchy of the 1 slave computer 20 is detailed below with reference to FIG.9. Each one of configurations of the lower hierarchies of the slave computers 30, 40 and 50 are substantially the same as the configuration for the slave computer 20, thus drawings and details for the configurations for the slave computers 30, 40 and 50 are omitted for simplification. As shown in FIG.9, each of the moving faders 23a through 23h is connected to the slave computer 20 via a respective one of motor drivers 25a through 25h.

Each of the moving faders 23a through 23h has a respective one of sliding resistors 26a through 26h each having a sliding contact, and a respective one of motors 27a through 27h for moving those sliding contacts of the sliding resistors 26a through 26h.

These movements of the sliding contacts vary the resistances between the sliding contacts and ground in the sliding resistors 26a through 26h. Each of the motor drivers 25a through 25h drive the respective one of the motors 27a through 27h so as to move the respective one of the sliding contacts of the sliding resistors 26a through 26h. The slave computer 20 provides directive signals to terminals Fin and Rin of the motor drivers 25a through 25h, the directive signals specifying the rotation directions of the motors 27a through 27h. Further, the slave computer 20 provides reference voltages causing the motor driver 23a to output driving voltages for determining the rotation speeds of the motors 27a through 27h, to terminals VREF of the motor drivers 25a through 25h, via a D/A (digital to analog) converter 20X, The slave computer 20 provides the reference voltage data in six-bit digital signals to the D/A converter 2OX, each of these six-bit digital signals being able to express 64 (26=64) steps accordingly.

That is, the six-bit digital signals can respectively control the rotation speeds of the motors 27a through 27h in 64 steps by varying the reference voltages causing the driving voltage applied to the motors 27a through 27h in the 64 steps.

Each of the sliding resistors 26a through 26h has a fixed resistor element having one terminal connected to a voltage terminal Vs and the other terminal connected to ground. Each of the above mentioned sliding contacts is located movably between the voltage and ground terminals. Each of the sliding resistors 26a through 26h divides the voltage applied between the voltage terminal and the ground terminal of the fixed resistor in proportion to the position of the sliding contact so as to output another voltage resulting from the above-mentioned voltage division from the sliding contact. This voltage signal, output from the sliding contact in each of the sliding resistors 26a through 26h of the moving faders 23a through 23h, is supplied to the slave computer 20 via an A/D (analog to digital) converter 20y.

Each of the above-mentioned motor drivers 25a through 25h is connected to a respective one of channel terminals chl through ch8 of the D/A converter 20X Each of the above-mentioned moving faders 23a through 23h is connected to a respective one of channel terminals chl through ch8 of the A/D converter 20y.

As mentioned above, the control signals for movements of the motors 27a through 27h are supplied to the terminals Fin, Rin and VREF of the motor drivers 25a through 25h, the motor drivers thus respectively providing the driving voltages to the motors 27a through 27h. Thus the driving voltages respectively appropriately drive the motors 27a through 27h, the motors 27a through 27h thus moving the corresponding sliding contacts of the moving faders 23a through 23h accordingly, the sliding contacts being mechanically connected to the corresponding motors 27a through 27h. This motion of each of the motors 27a through 27h results in moving another respective one of other sliding resistors (not shown in the drawings) for controlling, for example, sound volumes of various sounds, because, for example, the motors 27a through 27h are further mechanically connected to the other sliding resistors.

Further, each of the moving faders 23a through 23h, as mentioned above, respectively provides the voltage signal corresponding to the position of the respective one of the sliding contacts of the sliding resistors 26a through 26h, to the A/D converter 20y.

The A/D converter 20Y then converts that voltage signal to a corresponding digital signal so as to supply it to the slave computer 20.

This digital signal, acting as a feedback signal, facilitates a accurate control, by the slave computer 20, of the respective one of the moving faders 23a through 23h. This is because the slave computer 20 may appropriately vary (make a correction to) the above-mentioned control signal for the movement (rotation) of the motors 27a through 27h supplied to the motor drivers 25a through 25h (through terminals Fin, Rin and VREF via the D/A converter 20X), this varying of the reference voltage data being based on the digital signals acting as the feedback signals. As a result, it may be possible to optimally control the moving faders 23a through 23h, that is, rotation directions and/or speeds of the motors 27a through 27h, so as to obtain the above-mentioned accurate control behavior.

Details of control of each of the moving faders 33a through 33h, 43a through 43h and 53a through 53h by the corresponding one of the slave computers 30, and 50 are substantially the same as those of the control of each of the moving faders 23a through 23h by the slave computer 20 mentioned above, thus description of the details of the control of the moving faders 33a through 33h, 43a through 43h and 53a through 53h are omitted for the sake of simplification.

A control flow for controlling the moving faders 23a through 23h by the slave computer 20 is described below with reference to FIG.10. The above mentioned control directive is supplied to the slave computer 20 in a step S1 (the word "step" will be hereinafter omitted, thus the step will be expressed by an abbreviation such as, S1). The control directive specifies motions of the motors 27a through 27h of the moving faders 23a through 23h. In S2, the slave computer 20 then reads the above-mentioned 25_ identification code so as to determine whether or not the received control directive is for the slave computer 20 by checking whether or not the identification code coincides with the identification code previously assigned to the slave computer 20.

When the received control directive is not for it (No in S2), the slave computer 20 waits until it receives a control directive having an identification code coinciding with the identification code previously 1 assigned to it.

Then, after determining that the received control directive is for the slave computer 20 (Yes in S2). It is determined in S3 whether or not the current positions of the sliding contacts of the sliding resistors 26a through 26h of the moving faders 23a through 23h coincide with the target positions, the target positions being indicated by the control - directive provided from the master computer 10. Those current positions of the sliding contacts of the sliding resistors 26a through 26h are fed back to the slave computer 20 through the A/D converter 20y, as mentioned above. In S4, the slave computer 20 controls the moving faders 23a through 23h so that the motion of the sliding contact of a corresponding one of the sliding resistors 26a through 26h stops when it is determined in S3 that the current position of the corresponding sliding contact coincides with the corresponding target position.

On the other hand, S5 determines the direction of a corresponding one of the sliding contacts of the sliding resistors 26a through 26h, in which direction the current Position of the corresponding sliding contact differs from the target position, when in S3 it is determined that the position of the corresponding sliding contact does not coincide with the target position (No in S3). Then, S6 measures the distance between the current position of the corresponding sliding contact and the target position.

Then, S7 determines the magnitude of the above mentioned driving voltage to be applied to the corresponding one of the motors 27a through 27h for corresponding sliding contact, then determines the D above-mentioned reference voltage causing the corresponding motor driver to provide that driving voltage, the driving voltage being based on the distance measured in S6. Then the slave computer 20 provides the reference voltage to the above-mentioned terminal VREF of the corresponding one of the motor drivers 25a through 25h, via the D/A converter 20X The corresponding motor driver then applies the driving voltage determined in accordance with the reference voltage, supplied to the terminal VREF, to the corresponding one of the motors 27a through 27h. The polarity of the driving voltage applied to the corresponding motor is determined in accordance with the direction in which the current position of the corresponding sliding contact differs from the target position determined in S5. Then, either S8 or S9 rotates the corresponding motor forward or backward in accordance with the magnitude and the polarity of the driving voltage. Thus, the rotating direction of the motor is determined in accordance with the polarity of the driving voltage and the rotation speed of the motor is determined in accordance with the magnitude of the driving voltage.

By the above-mentioned steps, the rotations of the motor 27a through 27h are controlled so that the current positions of the sliding contacts of the sliding resistors 26a through 26h respectively coincide with the corresponding target positions specified by the master computer 10 through the above-mentioned control directives. Further, the master computer 10 simultaneously provides control directives to the other slave computers 30, 40 and 50 so as to specify the target positions of the sliding contacts of the sliding x 1 resistors in the moving faders 33a through 33h, 43a through 43h, and 53a through 53h, so that the corresponding motors are controlled.

Summarizing for the mixer 1, the master computer 10 has the plurality of slave computers 20, 30, 40 and 50 as the lower hierarchy. Each of the slave computers 20 ' 30, 40 and 50 individually controls the group of moving faders belonging to it, thiscontrol being based on the corresponding control directives provided from the master computer 10. In this configuration, the control directives provided from the master computer 10 are transferred to the slave computers 20, 30, 40 and 50 approximately immediately, the slave computers thus being above to approximately simultaneously control the corresponding groups of moving faders in accordance to the control directives. As a result, these moving faders 23a through 23h, 33a through 33h, 43a through 43h, and 53a through 53h can realize a accurate automatic playing of tunes by controlling various elements of the tunes such as volumes of given sounds and other elements with the appropriate timing relative to each other.

Further, the master computer 10, after sending the control directives for moving the sliding contacts of the sliding resistors of the above mentioned moving faders, sends another control directive to each of the slave computers 20, 30, 40 and 50, the control directive requesting that each of the slave computers provide a corresponding feedback signal to the master computer 10 indicating how the corresponding slave computer controls the corresponding moving faders. Each of the feedback signals is a signal corresponding to the abovementioned voltage - 26 1 signal, the voltage signal being supplied to the corresponding one of the slave computers 20, 30, 40 and via the AID converter 20y, as mentioned above, the voltage of the voltage signal varying depending on the position of the sliding contact of the sliding resistor of the corresponding one of the moving faders 23a through 23h, 33a through 33h, 43a through 43h, and through 53h.

The master computer 10, after sending the control directive requesting the provisions of the feedback signal to each of the slave computers 20, 30, and 50, closes each of the receiving switches 21, 31, 41 and 51 in succession, such that only one of the switches 21, 31, 41 and 51 can close at any time, that is, for example, when switch 21 is closed, the other switches 31, 41 and 51 must be opened. Thus the master computer 10 receives a feedback signal from one of the slave computers 20, 30, 40 and 50, by closing the corresponding one of the receiving switches 21, 31, 41 and 51. That is, the master computer 10 closes one of the switches 21, 31, 41 and 51 when the master computer intends to receive the feedback signal from the corresponding one of the slave computers 20, 30, 40 and 50. This method can prevent the feedback signals, respectively provided from the plurality of the slave computers 20, 30, 40 and 50, from colliding with each other. Thus, each of the slave computers 20, 30, 40 and 50 can send the feedback signal without regard to whether or not the other slave computers are sending the other feedback signals. Thus, each of the slave computers 20, 30, 40 and 50 can act individually without regard to how the other slave computers act.

This method enables it to be determined from 27 - 1 which one of the slave computers 20, 30, 40 and 50 the feedback signal received by the master computer 10 has come, by selectively closing one of the receiving switches 21, 31, 41 and 50. As a result, the master computer 10 has to have only one receiving terminal R=. Further, it is possible for each of the slave computers 20, 30, 40 and 50 to have the came configurations, in hardware and in software, as each other. Further, it is possible to determine the configuration of each of the slave computers 20, 30, 40 and 50 individually without regard to relationships between the respective slave computers 20, 30, 40 and 50. As a result, it is possible to simplify the configuration of the mixer 1.

Further, the master computer 10 may limit a closing period, during which the master computer 10 closes one of the receiving switches 21, 31, 41 and 51, to a predetermined duration. Then, the master computer 10 may determine that a problem has occurred in the first slave computer when the master computer 10 receives no feedback signal from the first slave computer during the predetermined closing period during which the corresponding first receiving switch is closed. Then, the master computer 10 sets on internal flag so as to keep note of the fact that no feedback signal is received from the first slave computer, the flag including an identification number indicating the particular slave computer, the flag comprising bits representing information such as indicating a possible 30 fault condition and indicating an alarm condition. Then the master computer 10 turns to the second one of the slave computers 20, 30, 40 and 50 from the first slave computer, that is, the master computer 10 closes 28 - 1 the corresponding second receiving switch after opening the first receiving switch.

Then, after completing processes for the second, third and fourth slave computers, as in one scanning cycle, that is, for example, after completing receiving the feedback signals from the second, third and fourth slave computers, the master computer 10 closes the above-mentioned first receiving switch again, noting the fact that a feedback signal has not been received from the corresponding above-mentioned first slave computer by means of the above-mentioned flag. The master computer 10 may determine that a serious problem, that the first slave computer cannot solve by itself, has occurred in the first slave computer, when, for the second time, the master computer 10 does not receive any feedback signal from the first slave computer during a closing period of the same duration as that of the above-mentioned predetermined closing period. Then, the master computer 10 may indicate the alarm condition via the above-mentioned indication device 10c. Then the master computer continues processing for the second, third and fourth slave computers, those slave computers being in normal operation condition, for example, the master computer 10 receiving the respective feedback signals by closing the second, third, and fourth receiving switches successively, as in another scanning cycle.

The above-mentioned method prevents an overall control operation of the mixer 1 from being held up even if a problem occurs in the first slave computer. Then, the mixer 1 can continue the overall control operation as a result of continuing immediately from the first process for the first slave computer to - 29 1 the second process for the second slave computer. That is, for example, the master computer 10 closes the second receiving switch for receiving the feedback signal from the second slave computer, then the master computer 10 sending a control directive, contents of the control directive being based on the feedback signal received. This continuation of the overall control operation of the mixer 1 results in an improvement of the reliability of the mixer 1.

Further, in the mixer 1, the master computer 10 sends a status request command for requesting the status of the slave computers, the status request command being one of the above-mentioned control directives. Then, each of the slave computers 20, 30, 40 and 50 always sends, in response to the abovementioned status request command, a status signal indicating the status of the slave computer, the status signal being one of the above-mentioned feedback signals. Thus the master computer 10 can always determine the current positions of the faders (the sliding contacts of the sliding resistors) of the moving faders through the status signals, by renewing the corresponding position information when the master computer 10 receives the status signal. Thus, when the operator (a human being) moves the faders of the moving fader.s manually, the new positions of the faders are transferred to the master computer 10. Then, the master computer 10 may provide information indicating the manual moving of the faders, externally, for example, through a signal obtained as a result of converting to MIDI signal.

A mixer 5 of a second embodiment of the control system according to the present invention is - 30 described below with reference to FIG.11. A master computer 410 corresponds to the master computer 10 in the above-mentioned mixer 1. Each of slave computers 420, 430, 440 and 450 corresponds to a respective one of the slave computer 20, 30, 40 and 50 of the mixer 1.

Each of receiving switches 421, 431, 441 and 451 corresponds to a respective one of the receiving switches 21, 31, 41 and 51. Further, each of transmission switches 422, 432, 442 and 452 individually accepts or rejects the above-mentioned control directives being provided to a respective one of the slave computers 420, 430, 440 and 450.

The transmission switches 422, 432, 442 and 452 can eliminate the above-mentioned identification codes needed for the mixer 1 of the first embodiment.

This is because the master computer 410 may close only one first transmission switch of the transmission switches 422, 432, 442 and 452, the first transmission switch being closed allowing the control directive to be transferred to the first slave computer, the first transmission switch connecting the first slave computer to the master computer 410. That is, the master computer 410 closes the first transmission switch when the master computer 410 intends to provide the control directive to the first slave computer. In this method, the transmission switches other than the first transmission switch are opened so as to prevent the control directive directed only to the first slave computer from being received by the other slave computers. In this method, the control directive directed only to the first slave computer can be reliably received by only the first slave computer through the corresponding first transmission switch.

1 Thus, it is not necessary that the identification code be included in the control directive provided by the master computer 410, the identification code corresponding to the corresponding one of the slave computers 420, 430, 440 and 450.

Further, it is possible that the extra bits, available as a result of eliminating the identification code from the control directive, can be used for transferring other data. As a result, the data transfer speed can be improved, the processing speed for the control operation thus able to be improved in the mixer 5.

An application of the control system according to the present invention is not limited to such a mixer. The control system according to the present invention can be applied to a control system for controlling a plurality of values simultaneously.

An advantage resulting from the present invention is summarized as described below. Which one of a plurality of executing means (the abovementioned slave computer) a received feedback signal is provided from can be determined, as a result of selecting of feedback passing means (the above- mentioned receiving switch). Thus, it is sufficient for the control means (the above-mentioned master computer) to have only one receiving terminal. This method also enables each one of the plurality of execution means to have the same configuration as the others, facilitating simplification of the overall configuration of the control system. Further, a problem occurring in any one of the plurality of executing means will not obstruct the overall control operation of the control system. This is because the overall control operation can be continued, as a result of continuing immediately - 32 1 to the action of another one of the plurality of the executing means. In conclusion, it is possible that the reliability of the control system is improved.

Further, the present invention is not limited to the above mentioned embodiments, and variations and modifications may be made without departing from the scope of the present invention.

1

Claims

1. A control system comprising: a plurality of execution means for executing predetermined actions, said plurality of execution means then providing feedback signals indicating conditions resulting from the execution of said predetermined actions; control means for controlling said plurality of executing means by applying control signals thereto so as to cause said plirality of execution means to execute said predetermined actions independently from each other; and feedback-signal passing means for selectively passing to said control means said feedback signals provided by said plurality of executing means, in a first predetermined order.

2. The control system according to claim 1, wherein said feedback-signal passing means comprises a plurality of switches, each of said plurality of switches connecting between a respective one of said plurality of execution means and said control means.

3. The control system according to Claim 1. or 2, - 34 wherein said predetermined actions are driving actions for moving members, said feedback signals comprising positions of said moving members.

4. The control system according to Claim 1, 2 or 3, further comprising control-signal passing means for selectively passing said control signals to said plurality of execution means in a second predetermined order.

5. The control system according to any of the 1Drecediniz claims, wherein said predetermined actions are controlling actions for various sorts of sounds for composing a music tune thereof.

6. The control system according to claim 5, wherein said controlling actions for various sorts of sounds are actions for controlling volumes of input sound signals.

9z

7. A control system substantially as 1 hereinbefore described with reference to FIGS.4 through 11 of the accompanying drawings.