Field device configured for wireless data communication

• US 7,233,745 B2
• Filed: 10/26/2001
• Issued: 06/19/2007
• Est. Priority Date: 10/27/2000
• Status: Active Grant

• Current Assignee: Schneider Electric Systems USA, Inc. (Schneider Electric SE)
• Original Assignee: Invensys Systems Incorporated (Invensys PLC)
• Inventors: Loechner, Michael
• Primary Examiner(s): Chan; Jason
• Assistant Examiner(s): WANG, QUAN ZHEN
• Application Number:
  US09/983,890
• Publication Number:
  US 20020065631A1
• Time in Patent Office: 2,062 Days
• Field of Search: 340/539.1, 340555-557, 340/636.1, 455/343.1, 455/41.2, 455/66.1, 455/127.1, 455/127.5, 455/522, 375/238, 375/353, 375/239, 375/259, 370/310, 370/349, 398/120, 398/128
• US Class Current: 398/128
• CPC Class Codes: G05B 19/4185 characterised by the network communication
• CPC Class Codes: G05B 2219/25283 Evaluate available energy prior to wireless transmitter-receiver activation
• CPC Class Codes: G05B 2219/31121 Fielddevice, field controller, interface connected to fieldbus
• CPC Class Codes: G05B 2219/31251 Redundant access, wireless and hardware access to fielddevices
• CPC Class Codes: G05B 2219/33182 Uart, serial datatransmission, modem
• CPC Class Codes: G05B 2219/33192 Radio link, wireless
• CPC Class Codes: G05B 2219/33198 Laser, light link, infrared
• CPC Class Codes: G05B 2219/33206 Ultrasonic
• CPC Class Codes: G05B 2219/34313 Power supply for communication delivered by, derived from 4-20-mA current loop
• CPC Class Codes: G05B 2219/34481 EFC explosion free control, intrinsically safe
• CPC Class Codes: Y02P 90/02 Total factory control, e.g. smart factories, flexible manufacturing systems [FMS] or integrated manufacturing systems [IMS]

Abstract

Field devices comprising a transmitter and/or receiver for wireless data communication are provided. It is proposed to evaluate the energy available for wireless data communication in data transmitting or data receiving field devices prior to activation of the transmitter and/or receiver of the field device.

Claims

1. A field device comprising:

a wireless transmitter configured to transmit data from the field device to a remote device when activated;

an interface coupled to a bus, wherein the bus supplies power and control signals to the field device through the interface, the power being insufficient to sustain operation of the wireless transmitter when the wireless transmitter is activated;

an energy buffer configured to store energy from the power supplied to the field device via the interface, and to supply the stored energy to the wireless transmitter while the wireless transmitter transmits data from the field device to the remote device to sustain operation of the wireless transmitter;

at least one actuator and/or sensor adapted to alter and/or sense a control and/or process variable in a manufacturing field,

a memory configured to store a data stream for transmission by the wireless transmitter, wherein the data stream is divided into multiple segments; and

a controller configured to, for each one of the multiple segments, evaluate an amount of the stored energy available in the energy buffer prior to activating the transmitter to transmit the segment and, when the evaluation indicates that the stored energy in the energy buffer is insufficient to sustain operation of the wireless transmitter during transmission of the segment, delay activation of the wireless transmitter for transmission of the segment until the stored energy in the energy buffer is sufficient to sustain operation of the wireless transmitter during transmission of the segment.

2. The field device of claim 1 wherein the transmitter and/or receiver is adapted to operate in the radio, visible light or ultrasonic frequency range.

3. The field device of claim 1 wherein the transmitter and/or receiver is adapted to operate in the infrared frequency range.

4. A field device comprising:

a wireless transmitter and/or receiver configured for wireless data communication between the field device and a remote device when activated;

an interface coupled to a bus, wherein the bus supplies power and control signals to the field device through the interface, the power being insufficient to sustain operation of the wireless transmitter and/or receiver when the wireless transmitter is activated;

an energy buffer configured to store energy from the power supplied to the field device via the interface, and to supply the stored energy to the wireless transmitter and/or receiver during wireless data communication to sustain operation of the wireless transmitter and/or receiver;

at least one actuator and/or sensor adapted to alter and/or sense a control and/or process variable in a manufacturing field;

a controller configured to evaluate an amount of the stored energy available in the energy buffer prior to activation of the transmitter and/or receiver and, when the evaluation indicates that the stored energy in the energy buffer is insufficient to sustain operation of the wireless transmitter and/or receiver during wireless data communication, delay activation of the wireless transmitter and/or receiver until the amount of stored energy in the energy buffer is sufficient to sustain operation of the wireless transmitter and/or receiver during wireless data communication.

5. The field device of claim 4 wherein the controller is adapted to split an input data stream into a plurality of data segments for subsequent wireless data transmission.

6. The field device of claim 4 wherein the transmitter and/or receiver is adapted to operate in the radio, visible light or ultrasonic frequency range.

7. The field device of claim 4 wherein the transmitter and/or receiver is adapted to operate in the infrared frequency range.

8. The field device of claim 7 wherein the transmitter and/or receiver comprises a coder unit adapted to

receive an input bit stream with first input bits having a bit pulse time period and a first bit pulse amplitude and second input bits having the bit pulse time period and a second bit pulse amplitude;

and to

code each input bit of the input bit stream such that each generated coded pulse has a pulse time period shorter than the bit pulse time period.

9. The field device of claim 8 wherein the coder unit is adapted to:

code each first input bit of the input bit stream into at least one first driving pulse for supply to the transmitter, each first driving pulse having a first driving pulse time period being shorter than the bit pulse time period and a first driving pulse amplitude;

code each second input bit of the input bit stream to a second driving pulse, the second driving pulse having the first bit pulse time period and an amplitude of zero.

10. The field device of claim 9 wherein the ratio between the first driving pulse time period and the bit pulse time period is 0.01 to 0.98.

11. The field device of claim 10 wherein the first driving pulse is synchronized to the first input bit or to the second input bit.

12. The field device of claim 11 wherein the ratio between the first driving pulse time period and the bit pulse time period is 3/16 according to a physical layer IrDA.

13. The field device of claim 10 wherein the ratio between the first driving pulse time period and the bit pulse time period is 3/16 according to a physical layer IrDA.

14. The field device of claim 8 wherein the coder unit is adapted to:

code each transition from the first input bit pulse amplitude to the second input bit pulse amplitude in the input bit stream into at least one third driving pulse for supply to the transmitter, each third driving pulse having a third driving pulse time period being shorter than the bit pulse time period and a third driving pulse amplitude;

code each transition from the second bit pulse amplitude to the first bit pulse amplitude in the input bit stream to at least one fourth driving pulse, each fourth driving pulse having the third driving pulse amplitude and a fourth driving pulse time period being larger or smaller than the third driving pulse time period and smaller than the bit pulse time period.

15. The field device of claim 14 wherein the ratio between the fourth driving pulse time period and the third driving pulse time is in the range of 16 to 1/16.

16. The field device of claim 8 wherein the coder unit is adapted to:

code each first input bit in the input bit stream to at least one fifth driving pulse having a fifth driving pulse time period being shorter than the bit pulse time period, wherein in response to each fifth driving pulse the transmitter transmits a waveform having a first frequency;

code each second input bit in the input bit stream to at least one sixth driving pulse having a sixth driving pulse time period being shorter than the bit pulse time period, wherein in response to the sixth driving pulse the transmitter transmits a waveform having a second frequency.

17. The field device of claim 16 wherein the ratio between the first frequency and the second frequency is in the range of 1/16 to 16.

18. The field device of claim 8 wherein the coder unit is adapted to

code each transition from the first bit pulse amplitude to the second bit pulse amplitude in the input bit stream to at least one seventh driving pulse having a seventh driving pulse time period being shorter than the bit pulse time period, wherein in response to each seventh driving pulse the transmitter transmits a waveform having a third frequency;

code each transition from the second bit pulse amplitude to the first bit pulse amplitude in the input bit stream to an eighth driving pulse having an eighth driving pulse time period being shorter than the bit pulse time period, wherein in response to the eighth driving pulse the transmitter transmits a waveform having a fourth frequency.

19. The field device of claim 18 wherein the ratio between the third frequency and the fourth frequency is in the range of 1/16 to 16.

20. The field device of claim 8 wherein the coder unit is adapted to:

code each first input bit of the input bit stream into at least one ninth driving pulse for supply to the transmitter, wherein in response to the ninth driving pulse the transmitter activates a first light emitting diode at a first infrared frequency;

code each second input bit of the input bit stream into at least one tenth driving pulse for supply to the transmitter, wherein in response to the tenth driving pulse the transmitter activates a second light emitting diode at a second infrared frequency.

21. The field device of claim 8 wherein the coder unit is adapted to:

code each transition from the first bit pulse amplitude to the second bit pulse amplitude in the input bit stream to at least one eleventh driving pulse, wherein in response to each eleventh driving pulse the transmitter activates a third light emitting diode at a third infrared frequency;

code each transition from the second bit pulse amplitude to the first bit pulse amplitude in the input bit stream to a twelfth driving pulse, wherein in response to the twelfth driving pulse the transmitter activates a fourth light emitting diode at a fourth infrared frequency.

22. The field device of claim 8 wherein the coder unit is adapted to execute a frame setup procedure when data is transferred according to a predetermined frame format.

23. The field device of claim 8 wherein the coder unit is adapted to execute a variable code selection.

24. The field device of claim 8 wherein the coder unit determines each driving pulse amplitude in compliance with a required data exchange distance.

25. The field device of claim 8 wherein the infrared transmitter comprises:

a light emitting unit connected to a power supply line and to ground and emitting infrared waveforms according to driving pulses outputted by the coder unit; and

the energy buffer is coupled across the light emitting unit for supply of energy thereto.

26. The field device of claim 25 further comprising a first resistor and a second resistor connected in series between the power supply line and the light emitting unit and that the energy buffer is connected to the node between the first resistor and the second resistor, wherein the first resistor is adapted to limit the charge current of the energy buffer.

27. The field device of claim 26 wherein the second resistor is variable to change the irradiance of the light emitting unit according to a predetermined data exchange distance.

28. The field device of claim 25 wherein the second resistor is variable to change the irradiance of the light emitting unit according to a predetermined data exchange distance.

29. The field device of claim 25 further comprising a voltage monitor to evaluate the energy stored in the energy buffer.

30. The field device of claim 7 wherein the transmitter and/or receiver comprises a decoder unit adapted to derive an output bit stream with first output bits having the bit pulse time period and the first bit pulse amplitude and second output bits having the bit pulse time period and the second bit pulse amplitude in response to output pulses of an infrared receiver.

31. The field device of claim 30 wherein the decoder unit is adapted to:

synchronize each infrared receiver output pulse to a center of the bit pulse time period;

decode the first output bit on occurrence of each infrared receiver output pulse; and

to

decode the second output bit in the absence of an infrared receiver output pulse.

32. The field device of claim 30 wherein the decoder unit is adapted to

synchronize each infrared receiver output pulse to the beginning of the bit pulse time period;

decode a transition from the first bit pulse amplitude to the second bit pulse amplitude on occurrence of each first infrared receiver output pulse having a first infrared receiver output pulse time period; and

to

decode a transition from the second bit pulse amplitude to the first bit pulse amplitude on occurrence of each first infrared receiver output pulse having a second infrared receiver output pulse time period.

33. The field device of claim 30 wherein the decoder unit is adapted to:

synchronize each infrared receiver output pulse to a center of the bit pulse time period;

decode the first output bit on occurrence of each infrared receiver output pulse outputted by the infrared receiver in response to a first transmission frequency; and

decode the second output bit on occurrence of each infrared receiver output pulse outputted by the infrared receiver in response to a second transmission frequency.

34. The field device of claim 30 wherein the decoder unit is adapted to:

synchronize each infrared receiver output pulse to the beginning of the bit pulse time period;

decode a transition from the first bit pulse amplitude to the second bit pulse amplitude on occurrence of each infrared receiver output pulse outputted by the infrared receiver in response to a received transmission signal having a third transmission frequency; and

decode a transition from the second bit pulse amplitude to the first bit pulse amplitude on occurrence of each infrared receiver output pulse outputted by the infrared receiver in response to transmission signal having a fourth transmission frequency.

35. The field device of claim 4 wherein the transmitter and/or receiver comprises a data display unit.

36. A manufacturing plant control system comprising:

at least one functional unit coupled to a central controller via a system bus;

at least one control bus coupling at least one field device to the functional unit;

wherein the at least one field device comprises;

a wireless transmitter and/or receiver configured for wireless data communication between the field device and a remote device when activated;

an interface coupled to the control bus, wherein the control bus supplies power and control signals to the field device through the interface, the energy being insufficient to sustain operation of the wireless transmitter and/or receiver when the wireless transmitter is activated;

an energy buffer configured to store energy from the power supplied to the field device via the interface, and to supply the stored energy to the wireless transmitter and/or receiver during wireless data communication to sustain operation of the wireless transmitter and/or receiver;

at least one actuator or sensor adapted to alter or sense a control or process variable in a manufacturing field; and

a controller configured to evaluate an amount of the stored energy available in the energy buffer prior to activation of the transmitter and/or receiver and, when the evaluation indicates that the stored energy in the energy buffer is insufficient to sustain operation of the wireless transmitter and/or receiver during wireless data communication, delay activation of the wireless transmitter and/or receiver until the amount of stored energy in the energy buffer is sufficient to sustain operation of the wireless transmitter and/or receiver during wireless data communication.

37. The manufacturing plant control system of claim 36 wherein the at least one field device comprising the transmitter and/or receiver is adapted for wireless remote access to field devices coupled to the at least one control bus.

38. The manufacturing plant control system of claim 37 wherein the at least one functional unit comprises a further transmitter and/or receiver for wireless data exchange with the at least one field device.

39. The manufacturing plant control system of claim 37 wherein the at least one functional unit comprises a further transmitter and/or receiver for wireless remote access to field devices coupled to the functional unit via a control bus.

40. The manufacturing plant control system of claim 37 wherein at least two field devices are provided with an transmitter and/or receiver for wireless data communication and that the field devices are coupled by a remote access data exchange network.

41. The manufacturing plant control system of claim 36 wherein the at least one functional unit comprises a further transmitter and/or receiver for wireless data exchange with the at least one field device.

42. The manufacturing plant control system of claim 41 wherein the at least one functional unit comprises a further transmitter and/or receiver for wireless remote access to field devices coupled to the functional unit via a control bus.

43. The manufacturing plant control system of claim 41 wherein at least two field devices are provided with an transmitter and/or receiver for wireless data communication and that the field devices are coupled by a remote access data exchange network.

44. The manufacturing plant control system of claim 36 wherein the at least one functional unit comprises a further transmitter and/or receiver for wireless remote access to field devices coupled to the functional unit via a control bus.

45. The manufacturing plant control system of claim 44, wherein at least two field devices are provided with an transmitter and/or receiver for wireless data communication and that the field devices are coupled by a remote access data exchange network.

46. The manufacturing plant control system of claim 36 wherein at least two field devices are provided with an transmitter and/or receiver for wireless data communication and that the field devices are coupled by a remote access data exchange network.

47. A method of exchanging data in a manufacturing plant control systems using wireless data communication, the method comprising:

receiving, at a field device, power from a control bus, wherein the field device includes a wireless transmitter and/or receiver configured for wireless data communication between the field device and a remote device when activated and the power is insufficient to sustain operation of the wireless transmitter and/or receiver when the wireless transmitter is activated;

storing energy from the power received at the field device from the control bus;

supplying the stored energy to the wireless transmitter and/or receiver during wireless data communication to sustain operation of the wireless transmitter and/or receiver;

evaluating an amount of the stored energy prior to activation of the transmitter and/or receiver for wireless data communication; and

when the evaluation indicates that the stored energy is insufficient to sustain operation of the wireless transmitter and/or receiver during wireless data communication, delay activation of the wireless transmitter and/or receiver until the amount of stored energy is sufficient to sustain operation of the wireless transmitter and/or receiver during wireless data communication.

48. The method of claim 47 further including segmenting an input data stream into data segments for subsequent wireless data transmission.

49. The method of claim 48 wherein evaluating the amount of the stored energy prior to activation of the transmitter and/or receiver for wireless data communication comprises evaluating the amount of the stored energy prior to activation of the transmitter and/or receiver for transmission of each data segment.

50. The method of claim 49 further comprising transmitting a related message to the transmitter to interrupt wireless data transmission until further energy is supplied to the field device when the evaluation indicates that the stored energy is insufficient to sustain operation of the wireless transmitter and/or receiver during wireless data communication.

51. The method of claim 48 wherein further comprising transmitting a related message to the transmitter to interrupt wireless data transmission until further energy is supplied to the field device when the evaluation indicates that the stored energy is insufficient to sustain operation of the wireless transmitter and/or receiver during wireless data communication.

52. The method of claim 47 further comprising transmitting a related message to the transmitter to interrupt wireless data transmission until further energy is supplied to the field device when the evaluation indicates that the stored energy is insufficient to sustain operation of the wireless transmitter and/or receiver during wireless data communication.

53. A computer-useable storage medium storing a program that is loadable into a memory of a field device that includes a wireless transmitter and/or receiver configured for wireless data communication between the field device and a remote device when activated, the program including software code for exchanging data in a manufacturing plant control system using wireless data communication by causing a controller of the field device to:

receive power from a control bus, the power being insufficient to sustain operation of the wireless transmitter and/or receiver when the wireless transmitter and/or receiver is activated;

supply the stored energy to the wireless transmitter and/or receiver during wireless data communication to sustain operation of the wireless transmitter and/or receiver;

evaluate an amount of the stored energy prior to activation of the transmitter and/or receiver for wireless data communication; and

when the evaluation indicates that the stored energy is insufficient to sustain operation of the wireless transmitter and/or receiver during wireless data communication, delay activation of the wireless transmitter and/or receiver until the when the evaluation indicates that the stored energy is insufficient to sustain operation of the wireless transmitter and/or receiver during wireless data communication, delaying activation of the wireless transmitter and/or receiver until the amount of stored energy is sufficient to sustain operation of the wireless transmitter and/or receiver during wireless data communication.