METHOD FOR DATA TRANSMISSION VIA A PARTICULARLY WIRED DATA TRANSMISSION CHANNEL AND DRIVE SYSTEM

Description

[0001] The invention relates to a method for data transmission via a wired data transmission channel and a drive system.

[0002] It is common knowledge that data can be transmitted over a data transmission channel.

[0003] From the DE 42 21 476 A1 An arrangement for regenerating a binary signal is known.

[0004] From the DE 10 2010 034 521 A1 A method for reception by a receiver of a node in a radio network is known.

[0005] From the EP 0 328 266 A2 The closest state of the art is a method for data transmission.

[0006] From the US 5 995 512 A is a high-speed multimedia network.

[0007] From the DE 10 2013 007649 A1 A method for operating a system is known.

[0008] The invention is therefore based on the object of increasing the safety of drive systems.

[0009] According to the invention, the object is achieved by the method according to the features specified in claim 1 and by the drive system according to claim 7.

[0010] The advantage here is that it is easy to determine whether the symbols were transmitted securely. If interference has occurred, an error state is indicated. The core of the invention is that a received digital data stream is digitally oversampled, and from this an evaluation signal is generated which can be used to identify unacceptably strong interference. An analog value is determined from the oversampling which represents the strength of the interference. If this analog value assumes unacceptable values, i.e. is in a range between the lower and upper threshold value, it is concluded that the symbol was not transmitted securely. If a large number of symbols are not transmitted securely, in particular if symbols which follow one another directly in time are all not transmitted securely, an error state is indicated and the data transmission channel is thus assessed as unacceptably poor.

[0011] The invention thus enables an evaluation of the interference during data transmission through the data transmission channel.

[0012] The invention is thus applicable when switching from another to the above-mentioned data transmission channel after its detection.

[0013] Alternatively, the invention can be used as an automated "cable break" notification in the field, i.e., in an industrial facility. The notification is then forwarded to a control center, where it is possible to distinguish between "external fault" and "defective line."

[0014] Furthermore, the invention can be used for the automatic detection of a cable break point, in particular for the determination of the position of the cable break point in the cable transmitting the data, which is led from the converter to the angle sensor of a drive.

[0015] Alternatively, the invention can also be applied to "big data." For example, the data collected as part of condition monitoring is recorded over longer periods and statistically evaluated. This will make it possible in the future, for example, to identify sources of interference in a system, particularly by determining a temporal correlation, or to detect or diagnose problems with the transmission medium, vibrations when a train passes by, or the like.

[0016] The invention will now be explained in more detail with the aid of schematic illustrations: In the Figure 1 The inventive method for evaluating a data transmission channel is schematically outlined.

[0017] In the Figure 2 two symbols of the data word transmitted via the data transmission channel are shown and the determination of the output signal ma of the evaluation unit 1 is illustrated.

[0018] In the Figure 3The method is illustrated by way of example using an undisturbed optimal reception signal 30 and a disturbed reception signal 31.

[0019] As shown in the figures, telegrams consisting of data words and thus also of symbols are transmitted via the data transmission channel.

[0020] Each of the telegrams has a preamble that has a special signal pattern so that synchronization can be carried out on the receiver side.

[0021] On the receiver side, this special signal curve is waited for and, after its detection, a synchronization signal 6 is generated, which starts a clock generator 4, which starts a clock signal, here also referred to as window clock 5.

[0022] The clock period of the clock signal is predetermined and equals the clock period specified on the transmitter side.

[0023] The output signal of the evaluation unit 1 is fed to an evaluation unit 2, whose output signal is fed to a comparison unit 3 for comparison with threshold values.

[0024] The assessment unit 1 works in the Figure 2 manner presented.

[0025] As an example, a first signal 21 and an inverted signal 22 are shown here.

[0026] In the evaluation unit, the signal 21 is sampled starting after the arrival of an edge of the clock signal, i.e. window clock 5. In the Figure 2 Fifteen sampling points are shown. At each sampling point, the accumulator signal acc(n) is incremented, starting with the value zero, if the received signal 21 has the value one, i.e., HIGH, at the respective sampling point. Otherwise, no incrementation occurs.

[0027] With an undisturbed, optimal received signal, a maximum value ma_max is thus obtained as the final value; otherwise, a lower value is obtained. This final resulting value is forwarded from evaluation unit 1 to evaluation unit 2 as the output signal ma(n) of evaluation unit 1.

[0028] The sampling times are preferably regularly spaced from each other in time.

[0029] In the example in Figure 2 With the same sampling of the inverted signal 22 shown, the accumulator signal acc(n) results in the constant value zero, which is thus forwarded to the evaluation unit 2 as the minimum value ma_min.

[0030] In Figure 3 The accumulator signal acc(n) is shown for an undisturbed signal 30, which is selected here as a received square wave signal, i.e. a signal having alternating 1 and 0.

[0031] The edges of window clock 5 are represented as signal A_clk. Because no interference occurs and the output signal ma(k) of the evaluation unit therefore only has the value ma_max or ma_min, and therefore no intermediate values, the evaluation of each edge of the clock signal A_clk is represented as reliable.

[0032] On the output side, the output signal S_B is thus issued as error-free, in Figure 3 i.e. as LOW.

[0033] In Figure 3 However, an example of a disturbed received signal 31 is also shown. Here, the accumulator signal acc(n) does not always reach the maximum value, but rather intermediate values.

[0034] The output signal of the evaluation unit 2 is fed to the comparison unit 3, wherein the signal ma(k) is monitored for exceeding a lower threshold value E_lower and for falling below an upper threshold value E_upper.

[0035] These thresholds are in the Figure 3For illustration purposes, they are shown for the accumulator signal acc(n), but are preferably applied to the signal ma(k).

[0036] The edges of window clock 5 are again represented as signal A_clk. However, since interference now occurs, the corresponding edges are evaluated as uncertain, which is Figure 3 graphically represented by the deformed arrowhead.

[0037] If a specified number of consecutive edges is evaluated as uncertain, the output signal S_B is output as faulty, in Figure 3 i.e., HIGH. This means that the data transmission channel is disrupted.

[0038] Depending on this output signal S_B, the data transmission rate is reduced. To do this, the receiver sends a message following the telegram, causing the sender to resend the telegram.

[0039] During this re-transmission, the clock rate is reduced, thus the window length is increased and the window clock 5 is reduced.

[0040] By retransmitting the symbols with a time-stretched transmission, the probability of error-free transmission increases.

[0041] The Input signal S_in(n) of evaluation unit 1 is a digital data stream with a width of 1 bit and the output signal of evaluation unit 1 is a digital data stream with a width of m bits, where m is an integer greater than 1. This enables fast evaluation. List of reference symbols

[0042] 1 Evaluation unit 2 Evaluation unit 3 Comparison unit 4 Clock generator 5 Window clock 6 Synchronization signal 21 First symbol 22 Second symbol 30 Optimal reception signal 31 Disturbed reception signal 32 Reliable clock signal 33 Uncertain clock signal H High L Low k Symbol count n Symbol count S_B Output signal S_in(n) Input signal Acc(n) Accumulator signal Ma(k) Output signal of evaluation unit 1 Ma_max Maximum value of the accumulator signal Ma_min Minimum value of the accumulator signal E_upper Upper threshold value E_lower Lower threshold value A_clk Evaluation clock

Claims

1. Method for transmitting data via a wired data transmission channel and for assessing the transmission quality of the data transmission channel, wherein a transmitter sends a digital data stream to a receiver via the data transmission channel, wherein the symbols (21, 22) of the data stream are sent in a first clock, wherein the digital data stream received by the receiver is oversampled in an analog manner with a second clock, wherein for each symbol (21, 22) the sum of the sampled values is determined by an assessment unit (1), and for each symbol (21, 22) a result value is determined by a comparison unit (3), the result value being HIGH if the sum exceeds a lower threshold (E_lower) and does not reach an upper threshold (E_upper), and otherwise being LOW, wherein the input signal S_in(n) of the assessment unit (1) is a digital data stream having a width of 1 bit, and the output signal (S_B) of the assessment unit (1) is a digital data stream having a width of m bits, m being an integer greater than 1, wherein the second clock is faster than the first clock, wherein, once a specified number of HIGH result values belonging to symbols (21, 22) transmitted one directly after another over time has been exceeded, the output signal (S_B) indicates an error state and a moving average of the result values is monitored for an impermissible degree of deviation from a third threshold, wherein, once the error state has occurred, the receiver sends information to the transmitter so that the respective telegram is sent again, with the symbols (21, 22) being transmitted over an extended length of time, that is to say with a slower first clock.

2. Method according to claim 1, characterized in that each item of data is included in a telegram, wherein the respective sent telegram comprises a preamble and symbols (21, 22) temporally following thereafter with a first clock, wherein the receiver generates a synchronization signal (6) on the basis of the received preamble, said synchronization signal being fed to a clock generator (4) which generates the first clock on the receiver side in a manner synchronous with the first clock of the transmitter.

3. Method for transmitting data via a wired data transmission channel and for assessing the transmission quality of the data transmission channel, wherein a data telegram is sent from a transmitter to a receiver, wherein the sent telegram comprises a preamble and symbols (21, 22) temporally following thereafter with a window clock (5), wherein the receiver generates a synchronization signal (6) on the basis of the received preamble, said synchronization signal being fed to a clock generator (4) which generates the window clock (5) on the receiver side, wherein an accumulator signal is set to zero at a respective edge of the window clock (5), wherein the received signal is sampled multiple times by an assessment unit (1) of the receiver during a respective window clock period duration, wherein, depending on the sampled value, the accumulator signal is or is not incremented, wherein the value of the accumulator signal reached at the end of the respective window clock (5) is output as a signal ma(k) and is compared with an upper and a lower threshold (E_upper, E_lower), wherein, if the value exceeds the lower threshold and does not reach the upper threshold, the transmission of the respective symbol (21, 22) is assessed as unsecure, wherein, once a specified number of symbols (21, 22) has been received and assessed as unsecure, an output signal (S_B) indicates an error state, wherein the input signal S_in(n) of the assessment unit (1) is a digital data stream having a width of 1 bit, and the output signal (S_B) of the assessment unit (1) is a digital data stream having a width of m bits, m being an integer greater than 1, wherein k is a natural number numbering the symbols (21, 22), wherein, once the error state has occurred, the receiver sends information to the transmitter so that the telegram is sent again, with the symbols (21, 22) being transmitted over an extended length of time.

4. Method according to any one of the preceding claims, characterized in that the sampled value is compared with a threshold, and HIGH is used if the sampled value exceeds the threshold and LOW is used if it does not reach the threshold.

5. Method according to any one of the preceding claims, characterized in that the specified number has a value between five and thirty.

6. Method according to any one of the preceding claims, characterized in that the error state is also indicated optically and / or acoustically and / or is sent to a connected computer.

7. Drive system for carrying out a method according to any one of the preceding claims, wherein the drive system comprises a converter-fed electric motor, wherein an angle sensor of the drive system senses the rotation angle position of a rotor of the electric motor, wherein the angle sensor acts as a transmitter and the converter acts as a receiver, wherein the transmitter and the receiver are suitably designed to operate the data transmission channel bidirectionally, characterized in that the transmitter and the receiver are suitably designed such that the transmitter sends a digital data stream to the receiver via the data transmission channel, wherein the symbols (21, 22) of the data stream are sent in a first clock, wherein the drive system is designed such that the digital data stream received by the receiver is oversampled in an analog manner with a second clock, wherein the drive system is designed such that for each symbol (21, 22) the sum of the sampled values is determined by an assessment unit (1) of the drive system, and for each symbol (21, 22) a result value is determined by a comparison unit (3) of the drive system, the result value being HIGH if the sum exceeds a lower threshold (E_lower) and does not reach an upper threshold (E_upper), and otherwise being LOW, wherein the input signal S_in(n) of the assessment unit (1) is a digital data stream having a width of 1 bit, and the output signal (S_B) of the assessment unit (1) is a digital data stream having a width of m bits, m being an integer greater than 1, wherein the second clock is faster than the first clock, wherein the drive system is designed such that, once a specified number of HIGH result values belonging to symbols (21, 22) transmitted one directly after another over time has been exceeded, the output signal (S_B) indicates an error state and a moving average of the result values is monitored for an impermissible degree of deviation from a third threshold, wherein the drive system is designed such that, once the error state has occurred, the receiver sends information to the transmitter so that the respective telegram is sent again, with the symbols (21, 22) being transmitted over an extended length of time, that is to say with a slower first clock.