Communications: electrical – Condition responsive indicating system – With particular coupling link
Reexamination Certificate
1998-03-17
2001-11-20
Pope, Daryl (Department: 2736)
Communications: electrical
Condition responsive indicating system
With particular coupling link
C340S679000, C340S686200, C340S315000, C340S315000
Reexamination Certificate
active
06320502
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method and an apparatus for transmitting data between a position measuring system and a downstream evaluating unit.
BACKGROUND OF THE INVENTION
Conventional position measuring systems for determining the position of two parts movable relative to one another, for instance on a machine tool, are as a rule connected via a certain number of signal transmission lines with a downstream evaluating unit, for instance a numerical controller. In principle, in transmitting various signals between the position measuring system and the downstream evaluating unit, the attempt is made to keep the number of signal transmission lines required as low as possible. Besides avoiding unnecessary cable-laying effort and expense, another object in the transmission of possibly desired additional signals is to keep the compatibility with the previously conventional number of signal transmission lines assured as much as possible.
From European Patent Application EP 0 660 209 A1 of the present applicant, a position measuring system is known which includes among other elements a read/write memory unit. The memory unit is used in particular for storing system-specific parameters, which can be transferred to the position measuring system for instance from the downstream evaluating unit. When the memory unit is read out, in turn, certain system-specific parameters are transferred from the position measuring system to the evaluating unit. The system-specific parameters that can be stored in the memory unit and read out again are parameters of the entire system, for instance comprising an evaluating unit, a machine tool, and a position measuring system, if the corresponding position measuring system is used in a machine tool. Specifically, this may involve the specification of the measurement system type, the width of the signal period, specifications on the measurement steps in the position measuring system, the form of output signals furnished, reference signal information, machine tool parameters, correction values for the generated signals, and many more.
With the aid of such a memory unit in the position measuring system, it is now possible for instance prior to the actual measurement mode to program the position measuring system in a suitable way, by modifying certain parameters in the memory unit. On the other hand, the evaluating unit used can also be adapted to the existing overall system, by transferring certain parameters from the memory unit to the evaluating unit.
For bidirectional transmission of the system-specific parameters between the position measuring system and the downstream evaluating unit, a separate signal transmission line may for instance be provided. However, this increases the aforementioned cable-laying effort and expense, and moreover in that case the desired compatibility with previous interface standards no longer exists.
The object of the present invention is therefore, in position measuring systems having a read/write memory unit and with the provision for transmission of system-specific parameters from and to an evaluating unit, to keep the expense for the requisite signal connections as low as possible. In particular, given the possible transmission of such system-specific parameters, compatibility with previous interfaces is also desired.
The transmission of incremental position information over a supply line between a position measuring system and an evaluating unit is known from German Patent Disclosure DE 195 04 822. However, this reference neither discusses how system-specific parameters should be transmitted as reliably as possible nor provides details on designing a suitable apparatus or a corresponding method.
SUMMARY OF THE INVENTION
One aspect of the present invention regards a method for transmitting data between a position measuring system and an evaluating unit that includes the steps of generating a system-specific parameter, transmitting the system specific parameter between a position measuring system and an evaluating unit over at least one supply line.
A second aspect of the present invention regards an apparatus for transmitting data between a position measuring system and an evaluating unit, the apparatus includes a position measuring system, an evaluating unit and at least one supply line connected to the position measuring system and the evaluating unit. A modulator unit is connected to the at least one supply line, the modulator unit prepares a system specific parameter that is transmitted over the at least one supply line.
Thus, instead of transmitting the system-specific parameters over a separate signal transmission line between the position measuring system and the evaluating unit, at least one already existing supply line between the position measuring system and the evaluating unit is used for this purpose.
Each of the aspects of the present invention provide the advantage of render the otherwise required signal transmission line and the corresponding additional effort and expense accordingly become unnecessary. On the contrary, the provisions of the invention assure that with the connections already typically present between the position measuring system and the evaluating unit, reliable bidirectional transmission of system-specific parameters is possible.
Each of the aspects of the present invention provide a number of possibilities, especially with regard to the way in which the system-specific data are transmitted over the supply line. Thus there are various possible ways to adapt the apparatus and method of the invention to applicable given conditions.
Further advantages, details and possible embodiments of the method and apparatus according to the invention will become apparent from the ensuing description of an exemplary embodiment in conjunction with the accompanying drawing.
REFERENCES:
patent: 4818111 (1989-04-01), Affa
patent: 5815086 (1998-09-01), Ivie et al.
patent: 6114947 (2000-09-01), Tondorf
Brinks Hofer Gilson & Lione
Dr. Johannes Heidenhain GmbH
Pope Daryl
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