Patent Number: 
Section: claims

1. A position measuring system for detecting an indicated position of a guide rod extending along a rectilinear path being rectilinear relative to a guide system and can be moved along the rectilinear path, the position measuring system comprising:a number of reed contact elements;at least one magnetic element for forming a magnetic field, said magnetic element connected to the guide rod;at least one of said reed contact elements is in each case configured within a detection region to detect the magnetic field whose field strength is greater at a location of said one reed contact element than a predefined threshold value when said at least one magnetic element approaches said one reed contact element, at least one of said reed contact elements disposed in an environment of the rectilinear path;an inductive measuring system for determining a position of the guide rod disposed in the environment of the rectilinear path, said inductive measuring system having a number of electric induction coils; anda circuit configuration having at least one ohmic resistance unit forming a series circuit with at least one of said electric induction coils, and forming a circuit loop with at least one of said reed contact elements. 2. The position measuring system according to claim 1, wherein said magnetic element is a permanent magnet. 3. The position measuring system according to claim 1, wherein said magnetic element has an end connected to the guide rod. 4. The position measuring system according to claim 1, wherein the detection region of at least one of said reed contact elements detects an end of the guide rod disposed in the indicated position. 5. The position measuring system according to claim 1, wherein the guide rod can be moved between a minimum extended position and a maximum extended position. 6. The position measuring system according to claim 1, wherein said at least one ohmic resistance unit is one of two ohmic resistance units forming said series circuit with said electric induction coil, one of said two ohmic resistance units respectively being connected to in each case one end of said electric induction coil, and said series circuit containing a plurality of said reed contact elements, each said reed contact element forming a circuit loop with one of said ohmic resistance units. 7. The position measuring system according to claim 1, further comprising a circuit group for determining an ohmic total resistance of said circuit configuration. 8. The position measuring system according to claim 1, further comprising a control unit containing:a current source for feeding a direct current into said circuit configuration;a first measuring unit for detecting a DC voltage component of a total voltage in said circuit configuration; anda second measuring unit for detecting an AC voltage component of the total voltage in said circuit configuration. 9. The position measuring system according to claim 8, further comprising a further circuit configuration connected to said control unit, said further circuit configuration having an electrical coil and configured to form and control an electric current in said further circuit configuration. 10. The position measuring system according to claim 9, wherein said electrical coil is aligned and disposed parallel to the rectilinear path. 11. A position measuring system for detecting an indicated position of a control rod of a nuclear facility, the position measuring system comprising:a guide system, the control rod extending along a rectilinear path being rectilinear relative to said guide system, said guide system containing a pressure resistant guide tube enclosing the control rod;a number of reed contact elements;at least one magnetic element for forming a magnetic field, said magnetic element connected to the control rod;at least one of said reed contact elements is in each case configured within a detection region to detect the magnetic field whose field strength is greater at a location of said reed contact element than a predefined threshold value, at least one of said reed contact elements connected to said guide system and is disposed in an environment of the rectilinear path;an inductive measuring system for determining a position of the control rod disposed in the environment of the rectilinear path, said inductive measuring system having a number of electric induction coils; anda circuit configuration disposed in the environment of the rectilinear path and having at least one ohmic resistance unit forming a series circuit with at least one of said electric induction coils, and forming a circuit loop with at least one of said reed contact elements.