DE2820574A1 - DATA MODEM - Google Patents

Description

description

The present invention relates generally to, and particularly relates to, digital data connections a device operating in multiplex operation, which has several digital data channels for transmission via a combined single transmission path. The invention sees a device for automatically changing the channel configuration and can be used especially in connection with digital data modems.

In the prior art, digital data modems are known which establish the connection with data processing systems at each end of a transmission channel, for example a telephone line. There are also known modems with several inputs which have several channels for connection to a similar plurality of channels of a connected data processing system. The multi-channel information is multiplexed for transmission over an individual line. The multiplex operation is usually ^{effected in the "1} DM method (time division multiplexing = time division multiplex operation), in which the channels are interleaved bit for bit. Of course, other multiplex methods are also known, and they can also be used in connection with the invention be used.

It is used to initiate a connection over a transmission line Generally known between modems to transmit a sequence of initial signals, sometimes called "Shaking hands" operation is referred to. Such signals can indicate when a data source should transmit data wishes or would like to have a channel ready for transmission. An example of the first alternative, like her

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is currently used, the RTS procedure ("request to send" = "wishes to send" or "ready for sending" = "ready to send"). Examples of the second alternative are the DTR method ("data terminal ready" = "data terminal ready") or the DSR method ("data set ready"). RTS lies only during a transmission before, while DTR is present during the whole time in which the data source is is in mutual exchange with a device such as a computer system. It is also known to use DCD signals ("data carrier detect" = "determine data carrier") and RLSD signals ("receive line signal detect" = "stelle Fixed receiving line signal "). It is not only known to provide DCD signals in the presence of a data carrier from a connected modem, but also to degrade DCD after receiving a coded reverse of the RTS signal (RTS). One commercial available modem of this type is the Milgo 96 MM modem. The signals used there can have particular advantages can be used in accordance with the present invention, as will be described below.

Known multiple-input modems contain the necessary circuitry in order to depend on manually entered To switch commands to different input configurations. Such a channel allocation or input reconfiguration is useful if the data traffic picture - as usual - changes relatively seldom. Then it is possible to set up an operating circuit diagram which from time to time requires the intervention of an operator, to change the operating mode. In addition, the activities of two operators who have a modem at each end of the transmission line must be visible operated manually, coordinated. IM the expensive phone lines to use it more efficiently, it seems expedient to have the option of dynamically setting the input configuration to remodel or rebuild, the data processing system

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and the modem system for quick and automatic resetting or rearrangement of the inputs without operator intervention work together.

The invention is therefore based on the object of the input configuration of modems without manual Revise or remodel the intervention. Furthermore, the operating mode should be switched in two by a transmission line connected modems are automatically coordinated. Another object of the invention is to provide a to enable dynamic reverse or reorganization of the input configuration, creating a modem or multiplexing itself can flexibly adapt to changing traffic patterns without being tied to operating plans, so that to everyone Time the available bandwidth is used optimally.

In order to achieve this, a circuit is provided according to the invention which is one of a connected device pending demand for a change in the multiplex arrangement (input or channel configuration) and automatically providing control signals which cause the multiplexing device to make the desired change to undertake.

It is proceeded according to the invention so that when a device with inlet / outlet channels to a first data modem forming inputs a change of the input (channel) configuration, this requirement is detected, stored and a notification of this is sent over a transmission path as an input remap request to a second connected modem. After a suitable delay which allows the second modem to switch to the appropriate input configuration, the first modem also switches, to whom the request for the reorganization of the input configuration from the data processing system was initially received, to the new input configuration. The data modem or

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Multiplexes at that end of the line where the requirement for a new input configuration occurs first, is treated as a management unit, while the multiplexer modem at the other end of the line is the slave modem. Switching the input configuration mode is demand-dependent, so that if a data source does not require a channel, its channel is on the active data sources is distributed.

According to a further feature of the invention, a modem user can take advantage of the use of timers (master clocks) in the control of a data processing system at two modem locations pull in order to operate synchronize between the two modems. In this way the direct synchronization of the "software" allows, so that the need for the transmission of synchronization information is eliminated.

Another important aspect of the invention is the provision of a sequence technique when switching from one input configuration to the next, when the aforementioned "handshake" signals are used as they are currently used in communication systems Modems occur. In this way, the structure of the machine setup (hardware) is greatly simplified, and the difficulties associated with adding and removing channels are eliminated.

A preferred embodiment of the invention is described below with reference to the drawings. In the Drawings shows:

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1 shows a simplified block diagram of the preferred embodiment of the subject matter of the invention;

Fig. 2 is a block diagram of the channel allocation circuit;

3 shows an illustration of the input configuration selection sequence according to the invention;

Fig. 4 is a flow chart showing the operation of the subject invention at Converting channels from active to inactive status;

5 shows an illustration of the preferred embodiment of the invention when converting channels an inactive to an active state;

6 is a schematic block diagram showing an input configuration selection circuit; and

Figure 7 is a schematic circuit diagram showing an input configuration shuffling circuit for use with either the master or slave modem of the preferred embodiment of the invention.

According to FIG. 1, a pair of modems 1, 13 are provided which are connected to one another by a transmission channel 15. Each modem 11, 13 is connected to a data processing system, such as a central computer, a data terminal or other peripheral unit. For example, the modem 11 can have multiple inputs on a central processing unit (CPU) 12, while the modem 13 with several inputs at different Data terminals (DTE) 14 is located. In a known manner, a multiple-input modem connects a plurality in multiplex mode of channels of connected processing equipment for the purpose of connection via a transmission line. For example A multi-input modem can multiplex four inputs 16 with each other, each of which is 2400 Bits per second so that a total transmission of

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9600 bits per second results. The partner modem unbundles the information arriving via one channel. Usually a two-way (two-way) transmission system with a four-wire line is used inserted so that the interlacing (multiplex) and disentangling (demultiplexing) operations at both ends of the transmission line.

In practice it is often desirable to change the channel or input arrangement. For example, if two Channels of a four-input device are not currently required to transmit data then one would like to be able to allocate the bandwidth of these channels to those channels that actually Transferring data. In this way, more efficient data transmission is achieved.

As indicated above, the known contain multiple input modems the necessary switching to switch between different input configurations based on manual commands to be switched back and forth. A typical method of data coding for a multi-input transmitter is shown in FIG. Although Fig. 2 is somewhat simplified, those skilled in the art will understand the structure quickly recognize this circuit.

As FIG. 2 shows, the allocation of bandwidth in a four-channel system can be determined by a multiplex time signal selection circuit 101 which selects time signals to be supplied to four multiplex / demultiplex units 103. The time selection circuit 101 is fed by a timer 105 and contains frequency components and logic circuits which derive four divided time signals which are interleaved with one another in a cyclical four-phase time sequence; φ ^, Φ ₂ ι $ 3 ^and 04 «Depending on one of the status of the

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Technique according to manually set code, the time phases are optionally assigned to the multiplex / demultiplex units 103 supplied. The phase outputs of the multiplex / demultiplex units become one 9600 bit / s signal from an OR gate 104 combined and put on a single line. The OR gate 104 feeds the 9600 bits / s data to a modem transmission circuit 106 where the data is transferred in the usual manner be modeled.

For example, if only two channels A and B of four channels A, B, C and D are required for data transmission are fed to the multiplex unit of these channels A, B two time phases, whereby the bit output over these two channels A, B is doubled, while the other two channels C, D remain inactive.

One way of interleaving the data bits at different speeds is shown below Tabel.

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TABLE A

Speed operating type channel

Data rate

Data provision

A Ö

9600 2 4800 4800 9600 4 2400 2400 2400 2400 9600 4 7200 2400 9600 5 4800 2400 2400 7200 2,4,5 4800 2400 7200 3 2400 2400 2400

vvwww WWVVW

VVWWW

VWVW VWVWW

\ ΐ

VV

VVWWWV VWWW

VWVWVW VVW

VVVWWV

4800

2,3,5 2400 2400

vvwww

According to the preferred exemplary embodiment of the invention, a modem 11 operating as a master modem receives a Input configuration or channel allocation request in coded form from a connected data processing system such as the central processing unit 12. The respective input configuration is through controlled by a code supplied by a shift register 17 or other storage unit. Of the code supplied by shift register 17 selects the input

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Configuration as with known multi-input modems done by manual selection. A comparator continuously compares the input configuration request of the unit 12 with that of the operating mode shift register 17. When the central Computing unit requests a different input configuration than is specified by shift register 17, then generated the comparator 19 shift register control signals, which correspond to a new operating mode code which must be made available by register 17. To a delay determined by the timer 21, the shift register control information is used to set the operating mode code to change in the shift register 17 and thereby a new input configuration in the multi-input modem 11 to manufacture.

The delay caused by the delay device 21 gives the second or subsequent modem 13 a sufficient period of time to in order to address and to set up an input configuration which is the one recently requested by the master modem 11 Input configuration corresponds. During this period of time, the master modem 11 transmits to the slave modem Signals received from modem 13 as a transmitted input configuration request be interpreted. A device acting in accordance with that of the master modem 11 then provides the input configuration of the Follow-up modems 13. In detail, the comparison device 23 makes the request for a new input configuration by comparing the request code with the mode indicated by the shift register 25 fixed. The comparator 23 in turn generates shift register control information, which change the operating mode display of the shift register 25 after a suitable delay, to change the input configuration of modem 13 change.

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To set up the device described above (Fig. 1), it is very advantageous to have a channel priority and a Establish conversion subordination to simplify circuitry and pre-existing modem line subordination to use. Therefore, in accordance with the preferred embodiment of the invention, there is an input configuration mode selection sequence established, which is shown in Fig. 3 and Table I below:

TABLE I.

Speed

Receipt of receipt

ABC

Resulting operating mode

Resulting input configuration

9600

X
X

I ο

0 0 0

4 or 2

24 24 24

24 24

24

7200

1 0

3 5

24 24

24

4800

JL

24

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e -

Operating mode through which this channel becomes active again because the time portion of this channel is different was assigned. Therefore, in accordance with the preferred embodiment of the invention, returns to reactivation of one channel the input configuration circuit back to operating mode 3, in v / which all channels are active. All active channels are removed until the desired status is reached. Since the channel A is always active, the DCD trash code for that channel (ADCD) is used to return to the highest Operating mode, namely 3, to designate and initiate. Mode 3 then becomes the normal DCD channel fall-off sequence used to return to the correct configuration.

An example of the sequence technique described above is illustrated in FIGS. In this example DTR (data terminal ready) signals are used as control code on the master side, which were originally created after the Operating mode 3 is organized, then switches to operating mode and finally to operating mode 5.

Fig. 4 shows the fall of channels between the Operating mode 3 and operating mode 1. Originally located the master modem is in the normal idle state of operating mode 3, in_which the DTR signals for channels A and D are logical S according to the logical convention of Table I. The following modem is located accordingly in the "idle" state of mode 3, and the DCD signals of channels A and D represent logic signals. On Change to operating mode 1 is initiated by the master modem when the DTR signals for channels B, C and D fall to zero at the same time. There is a delay of 200 milliseconds (ms) during which the DCD waste code for channels B, C and D on the following modem is transmitted. A time delay of 100 ms in the following modem allows this to determine the DCD case and the

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Initiate change via operating modes 5 and 4 to operating mode 1. Preferably are intermediate stations how operating modes 5 and 4 run through rapidly, as indicated by the time of 0.416 ms in FIG is. As a result of the longer delay in the master modem, the slave modem reaches operating mode 1 before the Master modem falls back into operating mode 1. This ensures that the slave modem is ready to operate is ready with the new master configuration. In a similar way Any number of active inputs can be hidden. If the master modem falls back into operating mode 1, the only remaining channel A resumes normal transmission at 9600 bit / s.

Fig. 5 illustrates the process of adding inputs when the system is from mode 1, in which only channel A is in operation, changes to operating mode 5 in which channels A, B and C operate. First of all, the master modem is in operating mode 1, in which the DTR signal for the Channel 1 is positive. Accordingly, the slave modem is in operating mode 1 and the DCD signal for channel A is positive. The change to operating mode 5 is initiated when the DTR signals for channels B and go up. A delay of approximately 200 ms is then provided, during which the master modem all Transmits markings to the slave modem and indicates the DCD signal for channel A if it is. In the following modem after the detection of the drop, a delay of 100 ms occurs within which the slave modem enters the Operating mode 3 switches, in which all four channels are in operation. Again, because of the different Time delays of the slave modem operating mode 3 before the master modem switches to this operating mode.

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If the master modem is in operating mode 3, so he finds that mode 3 is still not the right one because the DTR signal for channel D is low. Then we essentially that shown in Fig. 4 and above Run through the described process again to hide channel 5 and return to operating mode 5. The DCD trash code for channel 5 is transmitted to the slave modem, which after a delay on the Operating mode 5 falls back. A longer delay in the master modem leaves it after the slave modem Switch to operating mode 5, followed by normal transmission via channel A with 4800 bits / s and is recorded via channels B and C with 2400 bits / s each. Accordingly, FIG. 5 illustrates the technique of Return to an operating mode in which all channels are active in order to add inputs.

As shown above, the use of DTR and DCD signals has been contemplated because these are typical signals that are recognized during transmission between modems. However, others can as well Signals are used to provide mode codes for the master and slave modems. For example can use the signal known as RTS instead of the DTR signal described above in the master modem to indicate the Mode codes are used.

As already mentioned, a request signal can indicate when a data source wishes or wishes to transmit data Have a channel available for transmission would like to. An example of the first alternative is the RTS signal currently in use. An example of the the second alternative is the DTR signal. Which of these signals is used as the demand signal depends depends significantly on the nature of the data source. For example, if it is a tape reader, the main

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mainly in long blocks of a few minutes, which alternate with equally long idle times, it will normally be sufficient to use RTS as the request signal. RTS is only available during a transmission before, and the use of RTS allows bandwidth redistribution in the longer periods of time, if the data source is not transmitting and there is no RTS signal.

Such an approach will normally be impractical if the data source is a is interactive, for example a data processing terminal. One such interactive data source switches quickly between the transmit and idle states. A correspondingly quick change of operating mode but is undesirable. In this case, the request signal can therefore be formed by the DRT signal which is present during the time in which the data source is in interactive connection with a Central processing unit or a similar device is located at the following end of the transmission line. Then kick bandwidth redistribution only occurs when the data source drops the DRT signal because there is none further connection with the central processing unit is required.

As already indicated above, it is not only known to receive a DCD signal in the presence of a data carrier from To provide master modem, but also to reduce the DCD signal when receiving an encoded RTS signal. One conventional form of the encoded RTS signal is a string of ones for a predetermined interval, which may be about 200 ms in the case of channels B, C and D, although it is also possible that a specific digital code word is assigned to the coded RTS.

The slave modem recognizes a coded RTS signal in the

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Channels B, C and D. As described above, this process is delayed to be reliable Ensure detection (otherwise a false detection could be caused by a longer chain of ones that occur during normal data transmission).

6 shows a simplified block diagram of a Circuit that the input configuration in a master modem or a slave modem according to the above controls sequence and coding techniques described with reference to FIGS. 3 to 5. This circuit has a Size comparator 31, two timers 33, 35 and a shift register 37 indicating the operating mode. Of the Size comparator 31 compares the inverse of the channel operating signals B, C and D which are of the operating modes indicating shift register 37, with the inversion of the input DRT signals (with the master modem) or the input DCD signals (with the following modem). The channel operating signals are supplied by converting the shift register output code in a decoder 36. The inputs to the size comparator 31 are designated together with X and Y, respectively.

The ratio of X and Y indicates the type of channel remodeling required. For example, if it is necessary to change from operating mode 1 to operating mode 5, the ABCD input at X will be 0111, while the ABCD inputs at Y will have the value 0001. In this case, X > Y and the shift register automatically stores mode 3. The stored "mode 3" signal is delayed by timer 35 for a period of time as discussed above with respect to FIGS became. On the other hand, when X is less than Y, it indicates that a channel is to be removed. In this

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In this case, the shift register 37 is only reclassified to the next operating mode code, namely after a time delay provided by the timer 33. If after a stage the comparison returns to X < Y fails, the shift register 37 is stepped up again. Finally, if X equals Y, then there is an idle state in which the desired operating mode is the same as the channel operating configuration. From the From the above discussion it has become clear that the importance of comparison is to determine whether Channels need to be added or removed. Various logical schemes can be derived from this, in order to derive this indication from the relevant channel codes without thereby affecting the scope of the invention is left.

Fig. 7 illustrates in detail a circuit which, according to the preferred embodiment of Invention for controlling configuration conversion can serve both the master modem and the slave modem. The master / follow-up selection is made by a Control line which controls the multiplexer in the manner described below.

In master mode, the control signals, for example the DTR signals from four inputs 16, become a four-bit Locker 39 supplied. The contents of the locker are input through a multiplexer 41 Least Significants "control logic 43 and then one Comparator 45 supplied. The comparator compares the channel operating signals at input 6 with the output of the Control circuit 43 and feeds output control signals to a Shift timer 47 or a storage timer. The shift timer 47 and the storage timer are connected through a multiplexer 51 and control a mode-indicating shift register 53. The "X = Y"

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or "idle" output of the comparator 45 is sent to the Lock control logic 55 is fed back, which controls the operation of the lock 39.

A control line 57 selects the master or the slave operating mode of the circuit. In the master operating mode the multiplexer 41 is caused to send the output of the four-bit latch 39 to the control logic 43 transfer. In the follow-up mode, the multiplexer 41 routes the DCD signals from a rail the control logic 43. The control line 57 also allows the multiplexer 51 the 200 ms output of the shift timer 47 and the 2OOms output of the storage timer 49 the mode shift register 53 if it is the master mode. In case of Sequence mode, the 100 ms outputs of the storage and shift timers are selected by the multiplexer 51. The function of the multiplexer as gate circuits is known per se.

In the master mode, the lock 39 is normally scanned at high speed. However, if a State change is detected, such that a "quiescent" output of the comparator 45 indicates that the State X = Y no longer exists, then the lock control logic 25 causes the lock 39, the Specification of the newly desired operating mode to be fixed.

The lock control logic 55 includes an AND gate 59, a NAND gate 61 and a delay flip-f / lop 63. The AND gate 59 takes an input indicating X ^ Y and an input indicating the selected master operation. If these conditions are met, then that is Output of AND gate 59 as high as the output

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normally downshifted delay flip-flops 63. In this case, the NAND gate 61 produces a low output indicating the latch condition indexes and blocks the sampling timer via an AND gate 65. However, if X = Y or the Master mode is not selected, then a high output of the NUND gate 61 indicates the scanning state of the lock 39.

The delay flip-flop 63 operates when mode 3 is selected. In this case the ADTR signal changes (it sinks, like here discussed) to control the slave modem. To prevent the comparator from mistakenly determining an inequality and fix the low ADTR signal, the delay flip-flop responds to a memory command, so that locking (pinning) is inhibited until ADTR returns to its original (high) state accepts. As FIG. 4 shows, this is achieved by advancing the time of the delay flip-flop at baud rate causes its D input to be fed with the save command and its switch-back input with the ADTR signal will.

The latch 39 therefore prevents any interruptions or input changes until the input configuration circuit has fully implemented the previous changes. That way you can Control signals are generated, fed to the slave modem, and executed before new interrupts for other requests are accepted on input assignments.

The code selected by the multiplexer 41 is then transmitted to the control logic 43, in which the channel is lowest Significant priority is given. The existing channel

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least significant forces the more significant channel information into the active state, which is im essential to filling in the "ignore" states in Table I. The channel Α information is not affected by this circuit. Of the The operation and structure of the logical gate for the "least significant" is shown below Table II shown:

TABLE II

INPUT (R TG / DCD) * ABCD AXXO AXOL Λ011 AIII

OUTPUT (TO MAG. COWP) * A A A A A

B 0 0 0 1

C 0 0

1 1

D 0 1 1

* NOTE: NEGATIVE LOGIC

The size comparator, which can be a normal digital comparator, generates - as I said, "X > Y \ "X <Y» and »X = y-outputs. These each show that a channel mode is desired which is being established. The "rest" or "X = Y" exit of comparator 45 is fed back to control interlock control logic 55. The state "X ^ γ" leads the

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Lock operation on. The "X ^ Y" exit goes to the shift timer 47, which issues a shift command to the mode shift register 53, and after a period of time selected by the multiplexer 51 in the manner discussed above. The "X ^ Y" load triggers a load or store timer 49, causing the shift register 53 to have the "mode 3" code is loaded, namely after a period of time again selected by the multiplexer 51. Both the sliding timer as well as the load timer can be conventional counting circuits.

Upon receipt of a shift command from the shift timer the shift register quickly passes through its initial states until the comparator 45 determines equality. This logical function is shown in FIG. 7 by an AND gate, which is dependent on the shift signal supplies a time signal from the timer 47 to the shift register until the comparator 45 has the "idle" output If no equality occurs after operating mode 3 has been saved, then the X ^ JY output is wild of the comparison 45 is activated, whereby the shift sequence just described is initiated.

If the operating mode shift register 53 is not in the shift or load state, it indicates the operating mode at its outputs. This operating mode display can be fed to a suitable line to select either mode 2 or mode 4.

If accordingly a new channel configuration in the master mode is requested, the comparator 45 issues either a shift or a store command. These commands are delayed by the timers 47, 49 in a suitable manner.

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During this delay, the signals are sent over the channel to the slave modem. Specifically, channel drops are detected from the output of the four-bit latch 39 and the associated drop code is sent. The device used to transmit the waste code receives the lock output via lines 40 and is known per se. If it becomes necessary to store operating mode 3, the code supplied to the slave modem is transmitted by comparator 45 via line 42 after the load or memory information has been determined. At the end of the time cycle ¹ determined by the timers 47, 49, the appropriate shift or store command is transferred to the shift register 53. The output of the shift register is then fed back to the comparator 45 in order to determine whether a further change in the contents of the shift register is necessary or whether the equilibrium state has now been reached.

When configuring the slave modem, the locking device 39 switched off by the multiplexer 41. Basically, the circuit operation is still the same, however with the exception that the DCD signals the "Least Significant Input" logic and the comparator45 are fed. The timer multiplexer 51 selects a shorter period of time and a DCD command must be present for the duration of the time cycle for the Circuit reacts.

Within the scope of the invention, other methods can be used to switch the input configuration to be carried out at spatially separate modem locations. One such method is to use an FSK (frequency shift keyed) Second channel or a completely independent data path for the transmission of the synchronization information to be provided. Such a channel path can be within the

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Transmission system or by means of external equipment.

Another method allows the modem user to synchronize two systems using the input configuration is requested at the same time at predetermined times. For example, in the end one day the device that works together with each spatially separated modem (e.g. a computer or a data terminal) specify a specific channel for a specific data transmission. Since the Modem control device has a master timer at each modem location, is synchronization a simple matter using this master timer. Because of the synchronized master timers on each There is no need for signal transmission between the two data devices in the modem location. These are connected in such a way that they follow the request made at the interface of the data terminal occurs. Since every modem is subject to master control, this synchronization technique is called master / master synchronization. If after the master / Master procedure is being worked, a user can have direct "software" control of the input configuration by entering its own sync codes.

As can be seen from the preceding discussion, changes and modifications can be made to the described preferred embodiment of the invention can be made without deviating from the content and concept of the invention.

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Claims (2)

MILGO ELECTRONIC CORPORATION, incorporated under the laws of the State of Florida, Miami , Fla. (V.St.A.) Data modem Expectations Data modem to which a connected device automatically receives one of several requirements for a specific channel configuration by means for multiplexing a plurality of channels into one of a plurality of Configurations and depending on control signals to select the particular channel configuration to be assumed, and means for determining a request for a new channel configuration issued by the connected Device is delivered, as well as for automatic switching to the required new channel configuration the multiplex facility. 2. Multi-input data modem to which a request code is automatically supplied, which allows one of several configuration · codes represented by: GE / gj 809846/0972 _ 9 - a) means for allocating channels via a plurality of inputs in response to each of the plurality of configuration codes; b) a device for supplying a first configuration code to the channel allocation device, responsive to control signals to change that first code; and c) means for determining a difference between that provided by the first code represented configuration on the one hand as well as the represented by the request code Configuration on the other hand, as well as for generating at least one control signal for the under b) said device, depending on that determination, to convert the first code into a second of the mentioned configuration codes, the second code being the request code is equivalent to. Hf) 984fi / 0972