Transmitting and receiving unit, arrangement with two transmitting and receiving units, and method for operating a transmitting and receiving unit

Abstract

A transmitting and receiving unit (100), hereinafter referred to as the first transmitting and receiving unit (100), comprising a first transmitter (110) and a first receiver (120), and which can be placed in a free-beam connection (300) with a second transmitting and receiving unit (200), comprising a second transmitter (210) and a second receiver (220), wherein the first transmitting and receiving unit (100) has a display device with a plurality of individually activatable display elements, characterized in that the display device is a single-row bar display (140) with a plurality of individually activatable bar elements (B1-B10) and a control device (130) is connected to the single-row bar display (140), which can be operated in a dual-display mode in which it performs a dual display of two adjustment states simultaneously with the bar elements (B1-B10) of this single-row bar display (140).- in the dual-display mode, the control unit (130) displays, with one or more bar elements (B1-B10) of the single-row bar display (140), the received power (P2) of the first receiver (120), which defines the alignment between the first receiver (120) and the second transmitter (210) and thus a first adjustment state, and simultaneously the received power (P1) of the second receiver (220), which defines the alignment between the second receiver (220) and the first transmitter (110) and thus a second adjustment state.

Description

The invention relates to transmitting and receiving units which can be brought into a free-beam connection with another transmitting and receiving unit, to an arrangement having at least two such transmitting and receiving units, and to a method for operating transmitting and receiving units.A transmitting and receiving unit having the features according to the preamble of claim 1 is known from the laid-open specification of the international patent application WO 2005 / 055436 A2. The previously known transmitting and receiving unit has a display device in the form of an LED array with a multiplicity of individually activatable display elements in the form of LEDs.A further transmitting and receiving unit is known from European laid-open specification EP 1 233 283 A2.The object of the invention is to specify a transmitting and receiving unit, an arrangement having two transmitting and receiving units and a method for operating a transmitting and receiving unit, in which the respective adjustment state relative to another (second) transmitting and receiving unit can be displayed with particularly simple means, but nevertheless very clearly and easily readable.This object is achieved according to the invention by a transmitting and receiving unit having the features according to patent claim 1, by an arrangement having the features according to patent claim 12 and by a method having the features according to patent claim 14. Advantageous embodiments of the invention are specified in the dependent claims.According to the invention, it is provided that the transmitting and receiving unit has a single-row bar display with a plurality of individually activatable bar elements. A control device is connected to the single-row bar display, which control device is operable in a double display mode in which it carries out a double display of two adjustment states simultaneously with the bar elements of this bar display, wherein, in the double display mode, the control device displays, with one or more bar elements of the single-row bar display, the reception power of the first receiver, which defines the alignment between the first receiver and the second transmitter and thus a first adjustment state, and simultaneously the reception power of the second receiver, which defines the alignment between the second receiver and the first transmitter and thus a second adjustment state.An important advantage of the transmitting and receiving unit according to the invention is that it enables a double display mode in which two adjustment states can be displayed simultaneously by means of a single single-row bar display. A simultaneous display of two adjustment states by means of one and the same single-row bar display can be detected particularly easily and quickly by an operator, so that intuitively correct and thus time-saving adjustment of the transmitting and receiving unit-relative to the second transmitting and receiving unit-is made possible within the scope of the device mounting.A further important advantage of the transmitting and receiving unit according to the invention is that it can be manufactured particularly cost-effectively, since it makes do with a single single-row bar display for the representation of two adjustment states.With regard to the configuration of the bar display, it is considered to be particularly advantageous if all bar elements of the bar display are arranged in series one behind the other on a straight or curvilinear path.With regard to the control of the bar elements, it is advantageous if each of the bar elements of the bar display is assigned an adjustment state range defined by a reception power range and, in the double display mode, one of the bar elements is activated in each case when the reception power of the first and / or of the second receiver is in the respectively assigned reception power range or adjustment state range, and all remaining bar elements remain deactivated.The control device is preferably designed such that it assigns the adjustment state range with the worst adjustment state to a first bar element located at an edge of the bar display and assigns adjustment state ranges to all other bar elements such that the distance of the respective bar element from this first bar element-measured along the straight or curvilinear path on which the bar elements are located-is greater the better the adjustment state that the respectively assigned adjustment state range defines.With a view to a simple display of two different adjustment states, it is considered advantageous if the control device is designed in such a way that, in the case that the first and second adjustment states are located in different adjustment state ranges, it activates exactly two bar elements in the double display mode, namely a bar element for the first adjustment state and a bar element for the second adjustment state.The activation of the beam element for the first adjustment state preferably takes place differently from the activation of the beam element for the second adjustment state, namely differently in such a way that an assignment of the two activated beam elements to the first and second adjustment states is possible.A particularly simple assignment of the bar elements to the first and second adjustment states is possible if the control device is designed such that, in the case that the first and second adjustment states are located in different adjustment state ranges, it operates the bar element for the first adjustment state with a different brightness, a different color and / or a different flashing frequency than the bar element for the second adjustment state.With a view to a particularly simple and comprehensible display of two adjustment states, which are the same or similar, it is considered advantageous if the control device is designed such that, in the case that the first and second adjustment states are located in the same adjustment state range, it activates exactly one single bar element, namely the bar element for this adjustment state range, and deactivates all remaining bar elements.The double display of two adjustment states by a single bar element is preferably signaled by flashing at a predefined flashing frequency.If the first transmitting and receiving unit is in the double display mode, but if, in the absence of sufficient receiving powers, only one receiving power can be signaled by means of one of the bar elements, this state is preferably displayed as a fault state in which the single activated bar element is operated in a special flashing mode. The flashing frequency during the fault condition is preferably greater than the flashing frequency in the case of a fault-free double display of two adjustment conditions by a single bar element.It is also considered advantageous if the control device can alternatively be operated in an individual display mode in which the first adjustment state is displayed solely using the bar elements of the bar display.The control device is preferably designed such that it automatically switches from the single display mode to the double display mode if the difference between the reception powers of the first and second receivers exceeds a predefined threshold or the reception power of the first or second receiver falls below a predefined threshold for a predefined minimum period of time.With regard to a reverse switching, it is considered to be advantageous if the control device is designed such that it automatically switches from the double display mode into the single display mode if both adjustment states have reached or exceed a predefined minimum quality for a predefined minimum period of time and at the same time the temporal fluctuation of one or both adjustment states falls below a predefined fluctuation threshold.With regard to the display in the single display mode, it is considered advantageous if the control device is designed such that, in the single display mode, it controls the bar elements within the bar display in such a way that the adjustment state range with the poor adjustment state is assigned to a first bar element located at an edge of the bar display and the adjustment state ranges are assigned to all other bar elements in such a way that the distance of the respective bar element from this first bar element-measured along the straight or curvilinear path on which the bar elements are located-is greater the better the adjustment state which the respectively assigned adjustment state range defines, and, for the display of the first adjustment state in the single display mode, it activates that bar element in the adjustment state range of which the first adjustment state lies, and also activates all other bar elements, to which poorer adjustment state ranges have been assigned.The invention also relates to an arrangement having two transmitting and receiving units. With regard to such an arrangement, it is provided according to the invention that at least one transmitting and receiving unit, preferably both transmitting and receiving units, are designed as described above. With regard to the advantages of the arrangement according to the invention, reference is made to the above explanations in connection with the transmitting and receiving unit according to the invention.The invention furthermore relates to a method for operating a transceiver unit, referred to below as a first transceiver unit, which comprises a first transmitter and a first receiver and is or has been placed in a free-beam connection with a second transceiver unit, which comprises a second transmitter and a second receiver, wherein the first transceiver unit has a display device with a plurality of individually activatable display elements and wherein a measurement value indicating the reception power of the second receiver is transmitted from the second transmitter to the first receiver via the free-beam connection.According to the invention, with respect to such a method, it is provided that a single-row bar display with a plurality of individually activatable bar elements is operated as display device in a double display mode in which a simultaneous double display takes place with the bar elements of this single-row bar display, namely a display of the reception power of the first receiver, which defines the alignment between the first receiver and the second transmitter and thus a first adjustment state, and simultaneously the reception power of the second receiver, which defines the alignment between the second receiver and the first transmitter and thus a second adjustment state.With regard to the advantages of the method according to the invention, reference is made to the above explanations in connection with the transmitting and receiving unit according to the invention.Preferably, a switch is made automatically from a single display mode to the double display mode if the difference between the reception powers of the first and second receivers exceeds a predetermined threshold or the reception power of the first or second receiver falls below a predetermined threshold for a predetermined minimum time period.Conversely, i.e. from the double display mode to the single display mode, preferably a switch is made automatically when both adjustment states have reached or exceed a predefined minimum quality for a predefined minimum period of time and at the same time the temporal fluctuation of one or both adjustment states falls below a predefined fluctuation threshold.The invention is explained in more detail below with reference to exemplary embodiments; in this case, by way of example FIG. 1 shows an arrangement in which an exemplary embodiment of a transmitting and receiving unit according to the invention, referred to below as a first transmitting and receiving unit, is connected to a second transmitting and receiving unit, FIG. 2 shows, by way of example, the operation of the first transmitting and receiving unit according to FIG. 1 in a single display mode, FIG. 3 shows the operation of the first transmitting and receiving unit according to FIG. 1 likewise in the single display mode, but compared with FIG. 2 in the case of a different adjustment state, FIGS. 4-6 show, by way of example, the mode of operation of the first transmitting and receiving unit according to FIG. 1 in the double display mode, different adjustment states being shown in FIGS. 4, 5 to 6, FIG. 7 shows a further exemplary embodiment for a bar display which can be used in the first transmitting and receiving unit according to FIG. 1, and FIG. 8 shows, by way of example, the operation of the first transmitting and receiving unit according to FIG. 1 in the double display mode in the event of a fault.For the sake of clarity, the same reference numerals are always used in the figures for identical or comparable components.FIG. 1 shows a first transmitting and receiving unit 100 comprising a first transmitter 110 and a first receiver 120. The first transmitter 110 and the first receiver 120 are connected to a control device 130, which actuates the first transmitter 110 and evaluates the respective received signal of the first receiver 120. The reception power of the first receiver 120 is denoted by the reference symbol P 2 in FIG. 1.Connected to the control device 130 is a bar display 140 by means of which the control unit 130 can represent the respective adjustment state-related to a second transmitting and receiving unit. The bar display 140 includes bar elements B 1 to B 10 arranged in series and individually activatable.In the exemplary embodiment according to FIG. 1, the first transmitting and receiving unit 100 is in contact with a second transmitting and receiving unit 200 via a free-beam connection 300. The second transmitting and receiving unit 200 has a second transmitter 210, a second receiver 220 and a control device 230 which is connected to the second transmitter 210 and the second receiver 220. It also includes a bar display 240 connected to the controller 230.The two transmitters 110 and 210 are preferably optical transmission devices, for example in the form of lasers or light-emitting diodes. Alternatively, they can also be other types of transmitting devices with which free-wheeling connections can be established, for example microwave transmitters, radio transmitters, etc.The two transmitting and receiving units 100 and 200 can be used for transmitting user data within the scope of forming data networks; alternatively or additionally, they can be used as light barriers.In order to make possible an optimal alignment relative to the second transmitting and receiving unit 200 particularly quickly and easily during the mounting of the first transmitting and receiving unit 100, a visually quickly detectable display of the adjustment states is of particular importance; in order to achieve an intuitive mounting of the first transmitting and receiving unit 100, the two transmitting and receiving units 100 and 200 preferably work together as follows:The control device 130 controls the first transmitter 110 in such a way that it transmits a transmission signal S 1 in the direction of the second receiver 220 of the second transmitting and receiving unit 200. The transmission signal S 1 may contain payload data which is to be transmitted from the first transmitting and receiving unit 100 to the second transmitting and receiving unit 200.Depending on the alignment between the transmitting and receiving unit 100 and the second transmitting and receiving unit 200, the second receiver 220 receives the transmission signal S 1 well or only poorly; the respective reception power of the second receiver 220 is symbolized in FIG. 1 by the reference symbol P 1.The control device 230 measures the reception power P 1 of the second receiver 220 and generates a reception power measurement value M 1, which it sends back, alone or with other payload data to be transmitted, with the aid of the second transmitter 210 via the free-beam connection 300 to the first receiver 120 of the first transmitting and receiving unit 100.The first receiver 120 receives the received power measurement value M 1 of the second transmitter 210 and transmits it to the controller 130. The controller 130 also detects the reception power P 2 of the first receiver 120.Thus, there are two items of information in the control device 130, namely information about the alignment between the first receiver 120 and the second transmitter 210 in the form of a first adjustment state value JZ 1, which is defined by the reception power P 2 of the first receiver 120, and information about the alignment between the second receiver 220 and the first transmitter 110 in the form of a second adjustment state value JZ 2, which is defined by the reception power P 1 of the second receiver 220 and the reception power measurement value M 1, respectively.With a view to the most intuitive possible operability of the transmitting and receiving unit 100, in particular during assembly, it is considered advantageous if the control device 130 enables two display modes, namely a single display mode in which the first adjustment state value JZ 1 is displayed by the bar display 140 alone, and a double display mode in which both adjustment state values JZ 1 and JZ 2 are displayed simultaneously by the bar display 140.FIG. 2 shows an embodiment of the single display mode. In the exemplary embodiment according to FIG. 2, the bar display 140 is configured such that the bar elements B 1 to B 10 are arranged one behind the other in series on a rectilinear path R. Each of the bar elements B 1 to B 10 of the bar display 140 is assigned an adjustment state range defined by a reception power range. It is assumed below by way of example that the bar elements B 1 to B 10 are assigned the following reception power ranges-based on a reception power setpoint P 0.B1: 1% to 10% of a reception power target value P0B2: 11% to 20% of the reception power set point P0B3: 21% to 30% of the reception power target value P0B4: 31% to 40% of the reception power target value P0B5: 41% to 50% of the reception power target value P0B6: 51% to 60% of the target received power value P0B7: 61% to 70% of the reception power target value P0B8: 71% to 80% of the reception power set point P0B9: 81% to 90% of the reception power target value P0B10: 91% to 100% of the reception power target value P0The desired received power value P0 used can be, for example, the power value which the receivers should receive for the interference-free or at least low-interference transmission of user data via the free-beam connection 300. The target reception power value P0 is preferably permanently stored in the transmitting and receiving units 100 and 200.In the exemplary embodiment according to FIG. 2, the reception power ranges are selected to be of the same size; alternatively, they can also have different sizes.In the single display mode, the control device 130 will preferably actuate the bar elements within the bar display 140 in such a way that a first bar element B 1 located at an outer edge 141 of the bar display 140 is assigned the adjustment state range with the worst adjustment state (in this case therefore the range between 1 and 10% of the reception power setpoint P 0). All other beam elements B 2 to B 10 are assigned the adjustment state ranges in such a way that the distance of the respective beam element from this first beam element B 1-measured along the rectilinear path R-is the greater the better the adjustment state that the respectively assigned adjustment state range defines.In the single display mode, for displaying the first adjustment state or the first adjustment state JZ 1, that bar element is activated in the adjustment state range of which the first adjustment state lies; in addition, all remaining bar elements are activated to which poorer adjustment state ranges have been assigned.In the illustration according to FIG. 2, it is assumed by way of example that the reception power P 2 of the first receiver 120 and therefore the first adjustment state value JZ 1 is 65% of the reception power setpoint value P 0. In the case of such a reception power P 2, the control device 130 will activate the bar elements B 1 to B 7, whereas the bar elements B 8, B 9 and B 10 remain uncontrolled or inactive. The bar elements B 1 to B 10 can be, for example, lamps or light-emitting diodes which are switched on when activated and are switched off when deactivated.The activated bar elements B 1 to B 7 are marked in FIG. 2 by circles with the reference symbol S, which are intended to symbolise a lighting of the respective bar elements.FIG. 3 shows, for further explanation and for better understanding, the mode of operation of the first transmitting and receiving unit 100 in the single display mode, again by way of example for the case in which the reception power P 2 of the first receiver 120 is only 32% of the reception power setpoint P 0. In this case, as explained above in connection with FIG. 2, the control device 130 will actuate the bar display 140 in such a way that the first three bar elements B 1, B 2 and B 3 are activated, whereas the bar elements B 4 to B 10 remain inactive. The activated three bar elements B 1 to B 3 are symbolized in FIG. 3 again by means of circles and the reference symbol S.In summary, the control device 130 will actuate the bar display 140 in the single display mode in such a way that more bar elements are activated with greater reception power P 2 than with smaller reception power P 2.In conjunction with FIGS. 4, 5 to 6, the operation of the first transmitting and receiving unit 100 during the dual display mode will be described below. In the dual display mode, the controller 130 controls the bar display 140 to display both the orientation between the first receiver 120 and the second transmitter 210 and the orientation between the second receiver 220 and the first transmitter 110.FIG. 4 shows by way of example how the bar display 140 can be controlled in the event that the adjustment state value JZ 1 indicating the first adjustment state is 38% and is smaller than the second adjustment state value JZ 2 indicating the second adjustment state, which is 72%, for example.It can be seen that the control device 130 for visualizing the first adjustment state value JZ 1 activates only the fourth bar element B 4 of the bar display 140 and thus displays that the adjustment state value JZ 1 is in the range between 31% and 40% of the reception power setpoint P 0. The display of the second adjustment state value JZ 2, which lies in a reception power range between 71% and 80% of the reception power setpoint P 0, is carried out by means of the eighth bar element B 8 of the bar display 140.In the double display mode, therefore, in the two adjustment states described, exactly two bar elements are activated, namely the bar element B 4 and the bar element B 8, whereas all remaining bar elements are inactive.A viewer of the bar display 140 can thus easily recognize that one of the two adjustment states is between 31% and 40% and the other adjustment state is between 71% and 80%.In order to additionally enable a viewer of the bar display 140 to assign which of the two adjustment states the respective bar element B 4 or B 8 displays, a different actuation of the bar elements B 4 and B 8 is preferably carried out, for example in the form of different degrees of brightness, different colors and / or different flashing intervals of the two bar elements B 4 and B 8.With regard to the previously discussed intuitive device operation, it is considered to be particularly advantageous if, for signaling the first adjustment state, the fourth bar element B 4 is actuated without flashing (flashing frequency equal to zero), whereas the eighth bar element B 8 is actuated for visualizing the second adjustment state in such a way that it flashes (flashing frequency greater than zero). The flashing of the eighth bar element B8 is identified in FIG. 4 by two concentric circles and the reference symbol S'.Alternatively, both bar elements B 4 and B 8 can also be controlled in such a way that they both blink; in this case, a distinction is preferably made by different blinking frequencies.FIG. 5 shows, for further explanation, the activation of the bar display 140 by the control device 130 in the case where the second adjustment state is poorer than the first adjustment state or the second adjustment state value JZ 2 is smaller than the first adjustment state value JZ 1.In the illustration according to FIG. 5, the first adjustment state is visualized by the bar element B 9 and the second adjustment state is visualized by the bar element B 7. In order to make it possible to assign the bar elements B 7 and B 9 to the respective adjustment states, preferably a flashing of one of the two bar elements is again provided, preferably that bar element which represents the second adjustment state value JZ 2. The flashing of the seventh bar element B7 is identified in FIG. 5 by two concentric circles and the reference symbol S'.FIG. 6 shows, by way of example, the operation of the bar display 140 for the case in which the two adjustment states are in the same reception power ranges. In the exemplary embodiment according to FIG. 6, it is assumed by way of example that both adjustment states are in a range between 71% and 80% of the setpoint reception power value P 0.If both adjustment states are located in the same adjustment state range, the common reception power range or the common adjustment state range is visualized by means of a single bar element. In the exemplary embodiment according to FIG. 6, the visualization takes place by the bar element B 8, which is assigned to the reception power range between 71% and 80% of the reception power setpoint value P 0.In order to signal without doubt to a viewer of the bar display 140 that a double display actually takes place with the aid of the single bar element B 8, a special flashing frequency can be provided. The flashing frequency for the case that a bar element simultaneously visualizes two adjustment states is preferably different from the flashing frequency that a bar element has for the display of a single adjustment state (see above in the case of the double display of different adjustment state ranges).The flashing of the bar element B8 is represented in FIG. 6 by two concentric circles and the reference symbol S".With regard to a changeover from the dual display mode to the single display mode or vice versa from the single display mode to the dual display mode, it is considered advantageous if an automatic setting or changeover of the display modes, that is to say without operator intervention, is carried out by the control device 130.Preferably, the dual display mode is automatically set or the display mode is automatically switched from the single display mode to the dual display mode if the difference between the reception powers P 1 and P 2 of the first and second receivers 120 and 220 exceeds a predefined threshold or the reception power of one of the two receivers 120 and 220 falls below a predefined threshold for a predefined minimum period of time. The predefined threshold is preferably in a range between 10% and 20% of the setpoint reception power value P 0. The minimum time period is preferably 3 or more seconds.The automatic changeover to the double display mode is regularly carried out with devices that are not yet oriented or are poorly oriented, but it can also be brought about in a targeted manner by intentional interruption of the free-steel connection 300 by the operator (for example by intentionally covering the receiver with light-opaque material, such as a glove, during the course of assembly).Preferably, an automatic changeover from the dual display mode to the single display mode occurs if both adjustment states have reached or exceed a predefined minimum quality for a predefined minimum period of time or the two adjustment state values JZ 1 and JZ 2 have reached or exceed a predefined minimum adjustment value Jmin and at the same time the temporal fluctuation of one or both adjustment states falls below a predefined fluctuation threshold. The minimum adjustment value Jmin is preferably between 30% and 40% of the target received power value P0, and the fluctuation threshold is preferably between 5% and 10% of the target received power value P0. The minimum time period is preferably 8 seconds or more.In conjunction with FIGS. 1, 2, 3, 4, 5 to 6, the operation of the first transmitting and receiving unit 100 has been explained, which displays, inter alia, the reception power P 1 of the second receiver 220 of the second transmitting and receiving unit 200 in the dual display mode. In order to enable the second transceiver unit 200 to perform a corresponding dual display, the first transceiver unit 100 is preferably also designed such that it transmits the received power P 2 of the first receiver 120 in the form of a measured received power value to the second transceiver unit 200 by means of the transmitter 110. In this case, the second transmitting and receiving unit 200 can also be operated in a double display mode and a single display mode, as has been explained in detail above.The two transmitting and receiving units 100 and 200 are preferably of identical construction.FIG. 7 shows a further exemplary embodiment of a bar display 140 which can be used in the transmitting and receiving unit 100 according to FIGS. 1, 2, 3, 4, 5 to 6.In the case of the bar display 140 according to FIG. 7, the bar elements B 1 to B 7 are not arranged in series one behind the other on a rectilinear path, as is the case in the case of the bar display 140 according to FIGS. 1, 2, 3, 4, 5 to 6, but on a curvilinear or circular path R. Otherwise, the above explanations apply correspondingly in connection with the operation of the bar display 140, in particular in regard to the single display mode and the double display mode, so that reference is made to the above explanations in connection with FIGS. 1, 2, 3, 4, 5 to 6.FIG. 8 shows the transmitting and receiving unit 100 by way of example for the case in which, despite the double display mode, only a single adjustment state value or only one reception power can be displayed, because the other reception power is too small or is equal to zero. In this case, only the displayable adjustment state value (here, for example, by the bar element B 3) is displayed, and it is preferably signaled by flashing that it is only a single adjustment state and a fault appears to be present. The flashing frequency in the case of such a malfunction situation or potential malfunction situation is preferably different from the flashing frequency in the case of a true double display of two reception powers which lie in the same reception power range as is the case with the display according to FIG. 6. The flashing frequency in the case of interference according to FIG. 8 is preferably greater than that in the case of interference according to FIG. 6.The flashing of the bar element B3 is represented in FIG. 8 by three concentric circles and the reference symbol S"'.Although the invention has been illustrated and described in more detail by preferred exemplary embodiments, the invention is not restricted by the disclosed examples and other variations can be derived therefrom by the person skilled in the art without departing from the scope of protection of the invention.List of reference characters100 Transmitting and receiving unit 110 Transmitter 120 Receiver 130 Control device 140 Bar display 141 Edge 200 Transmitting and receiving unit 210 Transmitter 220 Receiver 230 Control device 240 Bar display 300 Free-beam connection B 1-B 11 Bar elements JZ 1 Adjustment state value JZ 2 Adjustment state value M 2 Received power measurement value P Track P 0 Received power setpoint value P 1 Received power P 2 Received power S Activated bar element S' Activated flashing bar element S" Activated flashing bar element S"' Activated flashing bar element S 1 Transmission signal

Claims

Transmitting and receiving unit (100), referred to below as first transmitting and receiving unit (100), which comprises a first transmitter (110) and a first receiver (120), and can be brought into a free-beam connection (300) with a second transmitting and receiving unit (200), which comprises a second transmitter (210) and a second receiver (220), wherein the first transmitting and receiving unit (100) has a display device with a plurality of individually activatable display elements, characterized in that - the display device is a single-row bar display (140) with a plurality of individually activatable bar elements (B1-B10), and - a control device (130), which can be operated in a double display mode, is connected to the single-row bar display (140), in that it carries out a double display of two adjustment states simultaneously with the bar elements (B1-B10) of this single-row bar display (140), - wherein, in the double display mode, the control device (130) displays, with one or more bar elements (B1-B10) of the single-row bar display (140), the reception power (P2) of the first receiver (120), which defines the alignment between the first receiver (120) and the second transmitter (210) and thus a first adjustment state, and simultaneously the reception power (P1) of the second receiver (220), which defines the alignment between the second receiver (220) and the first transmitter (110) and thus a second adjustment state.Transmitting and receiving unit (100, 200) according to Claim 1, characterized in that all the bar elements (B1-B10) of the bar display (140) are arranged one behind the other in a row on a straight or curvilinear path (R).Transmitting and receiving unit (100, 200) according to one of the preceding claims, characterized in that each of the bar elements (B1-B10) of the bar display (140) is assigned an adjustment state range defined by a reception power range and, in the double display mode, one of the bar elements (B1-B10) is activated in each case when the reception power of the first and / or of the second receiver is located in the respectively assigned reception power range or adjustment state range, and all remaining bar elements (B1-B10) remain deactivated.Transmitting and receiving unit (100, 200) according to Claim 3, characterized in that the control device (130) is designed in such a way that it assigns the adjustment state range with the worst adjustment state to a first bar element (B1) located at an edge (141) of the bar display (140), and assigns adjustment state ranges to all other bar elements (B2-B10) in such a way that the distance of the respective bar element from this first bar element (B1) - measured along the straight or curvilinear path (R) on which the bar elements (B1-B10) are located - is greater the better the adjustment state which the respectively assigned adjustment state range defines.Transmitting and receiving unit (100, 200) according to one of the preceding claims, characterized in that the control device (130) is designed such that, in the case that the first and second adjustment states are located in different adjustment state ranges, it activates exactly two beam elements (B4 and B8 or B7 and B9) in the double display mode, namely a beam element (B4, B9) for the first adjustment state and a beam element (B7, B8) for the second adjustment state, wherein the activation of the beam element for the first adjustment state takes place differently than the activation of the beam element for the second adjustment state, namely differently in such a way that an assignment of the two activated beam elements to the first and second adjustment states is possible.Transmitting and receiving unit (100, 200) according to one of the preceding claims, characterized in that the control device (130) is designed such that, in the case that the first and second adjustment states are located in different adjustment state ranges, it activates exactly two beam elements (B4 and B8 or B7 and B9) in the double display mode, namely a beam element (B4, B9) for the first adjustment state and a beam element (B7, B8) for the second adjustment state, wherein the beam element (B4, B9) for the first adjustment state is operated with a different brightness, a different colour and / or a different flashing frequency than the beam element (B7, B8) for the second adjustment state.Transmitting and receiving unit (100, 200) according to one of the preceding claims, characterized in that the control device (130) is designed such that, in the case that the first and second adjustment states are located in the same adjustment state range, it activates exactly one single beam element (B8), namely the beam element (B8) for this adjustment state range, and deactivates all remaining beam elements (B1-B7, B9-B10).Transmitting and receiving unit (100, 200) according to one of the preceding claims, characterized in that the control device (130) can alternatively be operated in an individual display mode in which the first adjustment state is displayed alone using the bar elements (B1-B10) of the bar display (140).Transmitting and receiving unit (100, 200) according to Claim 8, characterized in that the control device (130) is designed in such a way that it automatically switches from the single display mode to the double display mode if the difference between the reception powers of the first and second receivers (120, 220) exceeds a predefined threshold or the reception power (P1, P2) of the first or second receiver (120, 220) falls below a predefined threshold for a predefined minimum time period.Transmitting and receiving unit (100, 200) according to one of the preceding claims 8 to 9, characterized in that the control device (130) is designed in such a way that it automatically switches from the double display mode to the single display mode if both adjustment states have reached or exceeded a predefined minimum quality for a predefined minimum period of time or if, with a predefined minimum quality, the temporal fluctuation of one or both adjustment states falls below a predefined fluctuation threshold.Transmitting and receiving unit (100, 200) according to one of the preceding claims 8 to 10, characterized in that the control device (130) is designed in such a way that - in the single display mode it controls the bar elements (B1-B10) within the bar display (140) in such a way that the adjustment state range with the poor adjustment state is assigned to a first bar element (B1) located at an edge (141) of the bar display (140) and the adjustment state ranges are assigned to all other bar elements (B2-B10) in such a way that the distance of the respective bar element from this first bar element (B1) - measured along the straight or curvilinear path (R) on which the bar elements (B1-B10) are located - is the greater the better the adjustment state is, which defines the respectively assigned adjustment state range, and - for displaying the first adjustment state in the single display mode, activates that beam element (B3, B7) in whose adjustment state range the first adjustment state lies, and also activates all remaining beam elements (B1-B2 and B1-B6) to which poorer adjustment state ranges have been assigned.Arrangement having two transmitting and receiving units (100, 200), characterized in that at least one transmitting and receiving unit (100, 200) is designed according to one of the preceding claims.Arrangement according to Claim 12, characterized in that both transmitting and receiving units (100, 200) are designed according to one of the preceding Claims 1 to 11.Method for operating a transmitting and receiving unit (100), referred to below as a first transmitting and receiving unit (100), which comprises a first transmitter (110) and a first receiver (120) and is or has been placed in a free-beam connection (300) with a second transmitting and receiving unit (200), which comprises a second transmitter (210) and a second receiver (220), wherein the first transmitting and receiving unit (100) has a display device with a plurality of individually activatable display elements, and wherein a measured value (M2) indicating the reception power (P1) of the second receiver (220) is transmitted from the second transmitter (210) to the first receiver (120) via the free-beam connection (300), characterized in that, - a single-row bar display (140) having a plurality of individually activatable bar elements (B1-B10) is operated as a display device in a double display mode in which a simultaneous double display takes place with the bar elements (B1-B10) of this single-row bar display (140), namely a display of the reception power (P2) of the first receiver (120), which defines the alignment between the first receiver (120) and the second transmitter (210) and thus a first adjustment state, and at the same time the reception power (P1) of the second receiver (220), which defines the alignment between the second receiver (220) and the first transmitter (110) and thus a second adjustment state.

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