TECHNICAL FIELD

The invention relates to contact equipment for communication between electronic units in the form of terminal blocks mounted on mounting rails, preferably for use in process control systems.

BACKGROUND ART

When designing electronic equipment based on the use of printed circuit boards (PCBs) in flexible systems, it is common nowadays to mount the PCBs in cubicles or boxes with cubicle frames. Circuit boards (CBs) with different func¬ tions are combined into larger units by inserting the PCBs into the cubicle frames, in slots intended for the PCBs. Communication between the respective CBs is possible by the connection of buses to the CB. Such bus connection may be utilized both during internal communication between diffe¬ rent circuit boards and during system communication with a computer. (By circuit board (CB) we mean a PCB populated with electronic components . )

When using the above-mentioned technique in, for example, process computer systems, a large number of external transducers or actuators are used, which are to be connected to a process computer via interface CBs in the process computer system. The task of the interface CBs is to convert signals from transducers/actuators to a computer or vice versa. Normally, this connection is arranged by placing an optional number of terminal blocks in rows adjacent to the CBs on the cubicle frames. These terminal blocks serve as connection and distribution terminal blocks, to which external transducers are connected by cross- interconnections . From the terminal blocks there extend, in turn, connection leads to the CBs concerned. Voltage supply or other supply of the system may also be arranged by uti-

lizing the terminal blocks as contact and connection devices.

The above-mentioned terminal blocks are fixed to the cubicle frames on mounting rails in the form of rails, which are normally made of metal. The rails are usually provided with flanges, onto which the terminal blocks are normally snapped by means of snap-in members below the terminal block. Terminal blocks are then placed in rows side-by-side on the mounting rail. These rails are provided in standard designs, for example in accordance with DIN standard EN 50 022 and 50 035.

In a new development stage within this technical field with a possibility of constructing flexible electronic system equipment, it is desirable to introduce mounting rails where new types of terminal blocks are to communicate with each other or be supplied with currents, voltages or signals through conductor paths directly on the rails. Examples of such new types of terminal blocks are described in Swedish patent application No. 9002763-2, entitled "Process inter¬ face system", filed concurrently herewith. Many advantages can be gained by replacing the simple connection and distribution terminal blocks and the associated system CBs according to the prior art by corresponding terminal blocks comprising electronic units integrated into one another and where these terminal blocks with built-in electronics are given the possibility to communicate, for example, with one another or direct with a computer through conductors on the rail. Among other things, the need of cross-inter¬ connections (also called marshalling) can be eliminated. Also, it will be possible to move process monitoring and control units in process computer systems to a smaller cubicle comprising the mentioned new terminal blocks with electronic units closer to the member or members monitored in a process, from where only a bus or an optical fibre conveys communication with a process computer at a distance.

It is known to connect electronic units as, for example, interface units to serial and/or parallel buses. These are then not placed in or on a standard mounting rail.

There also exist on the market electronic units placed on a mounting rail, these unit then communicating with external equipment via special cabling. Among other things, this prevents free mixing of these electronic units with standard terminal blocks . In another embodiment of such electronic units intended to be fixed to mounting rails, these units are connected point by point, that is, no bus structure for communication is applied.

SUMMARY OF THE INVENTION

To distribute voltages to terminal blocks and/or make possible communication between different terminal blocks on a mounting rail or for direct communication with external electronic units, electrically conducting paths are arranged on the mounting rail. The conducting paths consist of elec¬ trically conducting strips of thin foils or elevated ridges of electrically conducting material applied to the mounting rail with insulating material between the conducting paths and the mounting rail. One or more conducting paths may occur parallel to one another.

The conducting paths are positioned on the flanges of the rail, on the upper or lower side thereof, either on one of or both of the flanges. Alternatively, conducting paths are provided on the bottom of the mounting rail, that is, on the surface which is bounded by the flanges of the mounting rail. It is, of course, possible to provide both flanges and rail bottom with conducting paths .

Terminal blocks of various kinds are placed and snapped onto the mounting rail. These terminal blocks are equipped with contact pins located below the terminal block for pre¬ determined contact with a certain conducting path on the

mounting rail which corresponds to the position of the con¬ tact pin on the terminal block. The contact pins are con¬ nected directly, or via a contact device, to any of the con¬ ducting paths and bring about good electrical connection between conducting paths on the mounting rail and the con¬ tact pins with a corresponding location on the terminal block.

BRIEF DESCRIPTION OF THE DRAWING

Figure 1 and Figure 2 illustrate two examples of different types of mounting rails with ^' flanges, the rails being provided with electrically conducting paths on an insulating foil or an insulating layer of some other kind.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Mounting rails 1, 2 of standard type, for example according to DIN standard, such as of type EN 50022, EN 50035 or another type, are provided with electrically conducting paths 3 on the surface or surfaces of the mounting rail. The conducting paths 3 consist of electrically conducting foils, ridges or elevations, for example a thin copper foil, in one or several foils, applied to an insulating layer 4, 5 in the form of, for example, a thin plate or foil. The insulating layer or layers 4, 5 with the conducting paths 3 is/are applied to the surface of the mounting rail. The layer 4, 5 may be self-adhesive or is applied against the rail surface by some other form of pasting or adhesion. Mounting rails 1, 2 may also be prefabricated so as to be provided from the start with the conducting paths 3 on insulating layers 5, in which case these layers 5 may be made in any optional manner. In that case it is also possible to integrate insulating layers 5 with the mounting rail 1, 2 itself as a constituent thereof.

As is shown in Figures 1 and 2, the conducting paths 3 are located on top of the flanges 6, 7 of the mounting rail and

also below these flanges if desirable. Alternatively, or as a combination, conducting paths are also located in the bottom 8 of the mounting rail. A conducting path 3 need not run along the entire extent of the mounting rail 1, 2. The insulating layer 4, 5 with conducting paths 3 is so wide that it covers only one flange 6 or both flanges 6, 7, or the bottom 8 of the mounting rail, or the entire width of the mounting rail, or any combination of these variants.

In another embodiment of mounting rails with conducting paths, the conducting paths are made in the form of printed circuit boards for electronic components . Also in this embodiment, the conducting paths 3 are in the form of con¬ ducting foils or surfaces on an insulating layer 4 which is applied to the mounting rail.

The mounting rails used in connection with the present in¬ vention may, of course, exhibit shapes entirely different from those described with reference to Figures 1 and 2. The inventive concept is applicable to an optional cross section of the mounting rail, also with, for example, more than two flanges.