Communication System and Method for Isochronous Data Transmission in Real Time

1. A communication system for isochronous data transmission, comprising: a real time-controlled Ethernet data network having at least one first communication device, which has a synchronized timer and is designed to transmit real time-critical data telegrams using a scheduled real time control; at least one bridge device; and at least one second communication device that is connected to the bridge device and has a device for supplying real time-critical data telegrams, each of which contains a predetermined transmission time, and that has a communication interface by means of which the real time-critical data telegrams are transmitted to the bridge device, wherein the transmission time is a time at which the bridge device has to forward a data telegram to the first communication device after previously having received the data telegram from the second communication device, and the communication interface does not support any real time-controlled data transmission, and wherein the bridge device comprises: (i) a timer, which is synchronized with the timer of the first communication device, (ii) a device for analyzing the transmission time of a real time-critical data telegram sent by the second communication device, and (iii) a control device, which controls the forwarding of the real time-critical data telegram to the at least one first communication device of the Ethernet data network as a function of the transmission time included in the real time-critical data telegram, so that the bridge device does not require a transmission schedule for forwarding the real time-critical data telegrams.

2. The communication system according to claim 1 , wherein the real time-critical data telegrams supplied by the second communication device each contain phase information, which defines the communication cycle within the real time-controlled Ethernet data network; and wherein the analysis device is designed for analyzing the phase information of a real time-critical data telegram received by the second communication device and the control unit controls the forwarding of the respective real time-critical data telegram in the desired communication cycle to the at least one first communication device of the Ethernet data network as a function of the analyzed transmission time and the analyzed phase information.

3. The communication system according to claim 1 , wherein the real time-controlled Ethernet data network forms a PROFINET IRT-based Ethernet data network; wherein the at least one first communication device is designed according to the PROFINET IRT Standard; and wherein the real time-critical data telegrams supplied by the second communication device have a data structure according to PROFINET IRT Standard.

4. The communication system according to claim 3 , wherein the transmission time and/or the phase information appear(s) in a predetermined location in the payload data field of a respective real time-critical data telegram.

5. The communication system according to claim 1 , wherein the number of a predetermined output port of the bridge device is contained in the real time-critical data telegrams supplied by the second communication device.

6. The communication system according to claim 1 , wherein the bridge device is implemented in a first communication device.

7. The communication system according to claim 1 , wherein the bridge device performs the function of a PROFINET synchronization master or a synchronization slave.

8. The communication system according to claim 1 , wherein the bridge device has a memory device for temporary storage of real time-critical data telegrams received from the second communication device.

9. The communication system according to claim 1 , wherein the bridge device is designed for reception of real time-critical telegrams, which are generated by the first communication device, and for forwarding these real time-critical data telegrams to the second communication device.

10. The communication system according to claim 9 , wherein the bridge device is designed to write the respective reception time into the time-critical data telegrams arriving from the first communication device.

11. The communication system according to claim 1 , wherein the communication interface is a standard Ethernet interface, a USB interface, a WLAN interface, a FireWire interface or a PCI interface.

12. A method of isochronous transmission of real time-critical data telegrams within a real time-controlled Ethernet data network, which contains at least one first communication device having a synchronized timer, the first communication device being designed to transmit real time-critical data telegrams using a scheduled real time control, the method comprising: supplying by a second communication device of at least one real time-critical data telegram in which a predetermined transmission time is included, the transmission time indicating a time at which a bridge device has to forward the data telegram to the first communication device after previously having received the data telegram from the second communication device; sending the real time-critical data telegram over a communication interface of the second communication device to the bridge device, which is connected to the real time-controlled Ethernet data network and has a timer that is synchronized with the timers of the first communication devices, wherein the communication interface does not support a real time-controlled data transmission; analyzing in the bridge device the transmission time that is transmitted in the received real time-critical data telegram; monitoring the transmission time with the help of the timer; and forwarding the received real time-critical data telegram from the bridge device to the at least one first communication device of the Ethernet data network at the transmission time included in the real time-critical data telegram, so that the bridge device does not require a transmission schedule for forwarding the real time-critical data telegrams.

13. The method according to claim 12 , wherein the received real time-critical data telegram is stored temporarily in the bridge device until the transmission time is reached.

14. The method according to claim 12 , wherein the real time-critical data telegram is forwarded already after analysis of the transmission time and before it has been received completely in the bridge device.

15. The method according to claim 12 , wherein the real time-critical data telegram supplied contains phase information, which defines the communication cycle within the Ethernet data network; wherein the phase information contained in the received real time-critical data telegram is analyzed; and wherein the real time-critical data telegram is forwarded from the bridge device to the at least one first communication device of the Ethernet data network in the defined communication cycle and at the defined transmission time.

16. The method according to claim 12 , wherein the number of an output port of the bridge device is contained in the real time-critical data telegram supplied; wherein the output port number contained in the received real time-critical data telegram is analyzed in the bridge device; and wherein the real time-critical data telegram is forwarded via the selected output port of the bridge device to the at least one first communication device of the Ethernet data network in the defined communication cycle and at the defined transmission time.

17. The method according to claim 12 , wherein the real time-controlled Ethernet data network forms a PROFINET IRT-based Ethernet data network; wherein the at least one first communication device is designed according to the PROFINET IRT Standard; and wherein the real time-critical data telegrams supplied by the second communication device have a data structure according to the PROFINET IRT Standard.

18. The method according to claim 17 , wherein the transmission time and/or the phase information and/or the output port number is/are written in a predetermined location within the payload data field of the real time-critical data telegram.

19. The method according to claim 12 , wherein the transmission time, the phase information and/or the output port number are removed from the real time-critical data telegram before forwarding of same.