The invention will now be explained in greater detail on the basis of an example of an embodiment shown in the drawing, the sole FIGURE of which shows as follows:
The control system serves, essentially, for fulfilling control tasks. Communication between the control system L and the measurement transmitter M1 occurs either via the 4-20 mA current loop or via digital HART signals. Measurement transmitter M1 can be a pressure measurement transmitter. Measurement transmitter M2 is e.g. a vortex measuring device, Prowirl 73, of the firm Endress+Hauser®.
The method of the invention will now be explained in greater detail. Via the communication connection KOM3, digital signals can be transmitted from the measurement transmitter M1 to the measurement transmitter M2. In order to accomplish this, only a slight re-programming of the measurement transmitter M2 is necessary. For the measurement transmitter M1, any pressure measuring device with a HART interface can be used. Since the control system L does not participate in this data exchange, changes in the control system programming are not necessary. This is of great importance.
In order to find the desired measured value and to be able to process it, the receiver measuring device M2 examines the signals incoming from the transmitting measurement transmitter for at least one characteristic value of the measurement transmitter M1. The measured value belonging to this characteristic value is then further processed in the measurement transmitter M2. The required pressure measured value is recognized via the units characterizing number, as established in the HART standard.
In order that the measurement transmitter M1 transmits its measured values to the measurement transmitter M2, the measurement transmitter M1 is placed in the HART® burst mode using an operating device (e.g. a handheld device). In this mode, measurement transmitter M1 transmits its measured values without need for a request from the control system L. Permanently available to the measurement transmitter M2, therefore, are the current measured values of measurement transmitter M1, so that then the current, derived, measured variables can also be determined in a computer unit provided in measurement transmitter M2.
In an alternative embodiment of the invention, measurement transmitter M2 monitors, during its start-up, the communication connection K2 for incoming burst reports. If such is not happening, then measurement transmitter M2 attempts to place measurement transmitter M1 into burst mode. If this is successful, then the above-described method for data transmission can be performed.
In a further, alternative embodiment of the invention, measurement transmitter M2 is operated in the master mode. In this mode, the master M2 cyclically reads-out the measured values of measurement transmitter M1. This mode permits, however, only one other master, e.g. the control system L. In this case, an operating unit can no longer be attached for the parametering of the measurement transmitter M1, or M2, as the case may be, since an operating unit must always function as master.
An essential advantage of the invention is that a specific measurement transmitter M2 can be used with different measurement transmitters M1, which come from different manufacturers, in order to determine a certain, dependent, measured variable from the measured values of these two measurement transmitters. A further aspect of the invention is that no changes in the programming need to be effected at the control system L. A further aspect of the invention is that measured values of the measurement transmitter M1 are transmitted digitally to the measurement transmitter M2—without loss in accuracy by e.g. a digital-analog, and subsequent analog-digital, conversion. The control system communicates with the measurement transmitter M1 and/or M2 independently of the communication connection KOM3. Only at measurement transmitter M2 are slight software changes necessary.
With the help of the method of the invention, a simple data transmission of measured values is possible between two measurement transmitters M1 and M2.
Number | Date | Country | Kind |
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103 52 307.3 | Nov 2003 | DE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/EP04/12478 | 11/4/2004 | WO | 00 | 3/5/2007 |