Method and system for transmitting data reliably

Abstract

A method and device for transmitting data reliably to at least one item of equipment is provided, wherein: from its initial clock H.sub.1, an item of equipment generates at least one first clock H.sub.1U from a rising edge of the initial clock H.sub.1 with a frequency F.sub.1U and a second clock H.sub.1D from a falling edge of the initial clock H.sub.1, with a frequency F.sub.1D, the item of equipment: reads the received data using at least one first rising edge of H.sub.1U and one falling edge consecutive to the first rising edge of H.sub.1U, then reads the received data using a first rising edge of H.sub.1D and a falling edge consecutive to the first rising edge of H.sub.1D, the four clock edges used being consecutive by 2F.sub.1, decodes at least the four messages using an error-correcting code, when at least one decoded message is correct, it uses the information contained in this message to drive a device linked to said item of equipment.

Claims

1. A method for transmitting data reliably to at least one item of equipment provided with an initial clock H.sub.1 in a system comprising at least one message-transmitting device working with a first clock H.sub.0, wherein it comprises at least the following steps: from its initial clock H.sub.1, at an initial frequency F.sub.1, an item of equipment generates at least one first clock H.sub.1U from a rising edge of the initial clock H.sub.1 with a frequency F.sub.1U and a second clock H.sub.1D from a falling edge of the initial clock H.sub.1, with a frequency F.sub.1D, values of the frequencies being defined as: $F_{1U}=F_{1D}=\frac{F_1}{2}=F_0\frac{F_0}{N_0}$ where F.sub.0 is the initial frequency corresponding to the transmitting item of equipment and N.sub.0 is the number of bits of the message, the item of equipment then executes the following steps: reading the received data using the first clock H.sub.1U at a frequency F.sub.1U and the second clock H.sub.1D at a frequency F.sub.1D and using at least one first rising edge of the first clock H.sub.1U followed by a falling edge of the first clock H.sub.1U consecutive to the first rising edge of the generated first clock H.sub.1U, then a first rising edge of the second clock H.sub.1D followed by a falling edge of the second clock H.sub.1D consecutive to the first rising edge of the generated second clock H.sub.1D, the four clock edges used being consecutive, decoding at least the four messages using an error-correcting code, when at least one message is decoded correctly, using information contained in this message to drive a device linked to said one or more items of equipment.

2. The method according to claim 1, wherein the data are communicated using a communication protocol implementing a correction of CRC error-correcting-code type.

3. The method according to claim 1, wherein the items of equipment are inverters delivering power to a rotating machine.

4. A system for transmitting data reliably to at least one item of equipment configured to drive a device, the system comprising a device having a clock H.sub.0 operating at a frequency F.sub.0, wherein an item of equipment is configured to: generate, from the initial clock H.sub.1 of the item of equipment, at an initial frequency F.sub.1, at least one first clock H.sub.1U from a rising edge of the initial clock H.sub.1, with a frequency F.sub.1U, and one second clock H.sub.1D from a falling edge of the initial clock H.sub.1, with a frequency F.sub.1D, values of the frequencies being defined as: $F_{1U}=F_{1D}=\frac{F_1}{2}=F_0\frac{F_0}{N_0}$ where F.sub.0 is the initial frequency corresponding to the transmitting item of equipment and N.sub.0 is the number of bits of the message, read the received data using at least a first rising edge of the first clock H.sub.1U and a falling edge consecutive to the first rising edge of the generated first clock H.sub.1U, then read the received data using a first rising edge of the second clock H.sub.1D and a falling edge consecutive to the first rising edge of the generated second clock H.sub.1D, the four clock edges used being consecutive by 2F.sub.1, and decode at least the four messages using an error-correcting code, if the verification of at least one message with the error-correcting code is correct, use information contained in the message to generate a drive signal for a device linked to said one or more items of equipment.

5. The system according to claim 4, wherein the data-transmitting device is configured to use a communication protocol having a CRC error corrector.

6. The system according to claim 4, wherein the data-transmitting device is linked to a plurality of inverters configured to generate power and to deliver said power to a rotating machine.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Other features and advantages of the present invention will become more clearly apparent on reading the description of example embodiments, which are given by way of completely nonlimiting illustration, with reference to the figures, which show:

(2) FIG. 1A, an illustration of the use of a clock dedicated to the read-out of data, and FIG. 1B, the use of two clocks according to the prior art,

(3) FIG. 2, an example of implementation of the invention,

(4) FIG. 3, a schematic illustrating the generation of the two clocks according to the method of the invention, and

(5) FIG. 4, an example of a timing diagram for the read-out of data using the method according to the invention.

DETAILED DESCRIPTION

(6) In order to allow the method according to the invention to be clearly understood, the following example is given by way of completely nonlimiting illustration with respect to a system comprising a plurality of inverters that are configured to deliver power (energy) to a rotating machine, such as shown in FIG. 2. These inverters must be able to deliver power simultaneously, in order to prevent returns of power via the wires, which could adversely affect operation, and instead to obtain a summation of the power. In FIG. 2, for the sake of simplicity, only the detail of the link of one item of inverting equipment has been shown.

(7) FIG. 2 comprises a data-transmitting device 20 that transmits data D, comprising at least one clock H.sub.0 operating at a frequency F.sub.0 and one data-transmitting module 21.

(8) The data D contained in a message M are transmitted by means of a communication protocol, which is known to those skilled in the art and will not be detailed here, to an item of equipment 23 such as an inverter configured, for example, to generate power for a rotating machine 30. The item of equipment configured to generate power comprises a clock H.sub.R, a module 24 for generating two clocks H.sub.1D, H.sub.1U, from an initial first clock H.sub.1, a message-receiving module 25, and a data-processing module 26, such as a processor, that will process the received data at the rate of the two clocks, using the clock edges, according to the steps of the method according to the invention described below, in order to determine the one or more correctly read or decoded data. These data will then be used by a power-generating module 27 to deliver power, on reception of a control signal, to the rotating machine 30.

(9) FIG. 3 illustrates an example, for generation of the two clocks obtained from the initial clock, of operation of an item of equipment, said clocks being used for the read-out of the data received by the item of equipment.

(10) TABLE-US-00001 300 Clock of the transmitting item of equipment at a frequency F.sub.0 301 Clock of the receiving item of equipment at an initial frequency F.sub.1 302 Clock generated on the rising edges at a frequency F.sub.1U 303 Clock generated on the falling edges at a frequency F.sub.1D

(11) The clock-generating module considers the initial clock H.sub.1 of the receiving module of the item of equipment and generates:

(12) a first clock H.sub.1U by considering a first rising edge 310 of the initial clock H.sub.1 in order to generate a first rising edge 320 of the first clock H.sub.1U, a second rising edge 312 of the initial clock H.sub.1 in order to generate a first falling edge 321 with a frequency F.sub.1U,

(13) a second clock H.sub.1D by considering a first falling edge 311 of the initial clock H.sub.1 in order to generate a first rising edge 330 of the second clock H.sub.1D, a second falling edge 313 of the initial clock H.sub.1 in order to generate a first falling edge 331 of the second clock H.sub.1D with a frequency F.sub.1D.

(14) FIG. 4 illustrates the sequencing of the read-out of the data based on the two clocks H.sub.1U and H.sub.1U.

(15) The transmitting item of equipment of the data-transmitting device sends a message containing data D, 400, of N.sub.0 bits in size at a frequency F.sub.0, 300. The transmission may be carried out using a communication protocol known to those skilled in the art, implementing a method for verifying the transmission of data of CRC (cyclic redundancy check) type, for example.

(16) The initial clock H.sub.1 of the receiving module of the item of equipment operates at a frequency F.sub.1, 301 and allows a first clock H.sub.1U, 302 and a second clock H.sub.1D, 303 to be generated, as was explained above with reference to FIG. 3.

(17) The frequency F.sub.1 is equal to 2F.sub.0 with an error

(18) $<2\frac{F_0}{N_0}.$

(19) The data will be read out using the two generated clocks of frequency F.sub.1U and F.sub.1D, respectively, using two consecutive edges of the first clock H.sub.1u and two consecutive edges of the second clock FH.sub.1D (four consecutive edges). Thus the read-out is performed on a rising edge of H.sub.1U, followed by a falling edge of H.sub.1U, at a frequency F.sub.1U, followed by a rising edge of H.sub.1D, followed by a falling edge of H.sub.1D at a frequency F.sub.1D with the relationships:

(20) $F_{1U}=F_{1D}=\frac{F_1}{2}=F_0\frac{F_0}{N_0}$

(21) The frequency F.sub.0 of the transmitter and the frequency F.sub.0+/ of the receiver are not strictly identical and the difference between the two items of equipment may be

(22) $\mathrm{.Math.}\frac{F_0}{N_0}.$

(23) In addition, even it the phase of the two items of equipment is different, data may be transmitted safely and certainly between the two items of equipment if the two items of equipment have the same operating frequency F.sub.0.

(24) In the example given by way of illustration, the frequency is 1 Hz and therefore the period is 1 s. The number of bits to be transmitted is eight. Therefore the maximum tolerated offset for the clocks is =0.125 s. The required tolerance will depend on the size of the message.

(25) The receiver reads the message at four successive edges: On the rising edge of H.sub.1U, 441, M1 received data, 451, On the falling edge of H.sub.1U, 442, M2 received data 461, On the rising edge of H.sub.1D, 443, M3 received data 471, On the falling edge of H.sub.1D, 444, M4 received data 481.

(26) The four read-outs M1, M2, M3 and M4 are transmitted to the data-processing module, which will use an error-correcting method, for example a CRC code, in order to determine the one or more correct messages.

(27) When at least one single of the four messages is correct, then the processing module deduces therefrom that the transmitted original message is perturbed. In this case, it does not take into account the decoded message and will restart a cycle of reading and decoding the message until a correct decode is obtained.

(28) In the case where at least one message is decoded correctly (decoded message correct and corresponding to a reliable message) after application of a CRC error-correcting code, then the processing module concludes that the message is reliable, and that the data contained are also reliable and may be used to drive a device.

(29) In the case of application to delivery of power to a rotating machine, synchronization of the transmission of the control signal for the items of equipment delivering power to the rotating machine is thus ensured and any returns of current via linking lines between the various items of equipment, which could be detrimental to the correct operation of the machine, or even damage it, are thus avoided.

(30) The method according to the invention advantageously allows the message to be read out while detecting any possible errors, without using a dedicated clock line. The tolerance between the clocks of each item of equipment of the system has no impact on the result of the read-out. The method avoids message retransmissions that decrease useful bandwidth.