Arrangement for coded and uncoded plug-in modules and device for connecting external lines using the arrangement

A device for encoding plug-in modules reliably prevents a plug-in module with a 24 V direct voltage supply from being inserted directly to the right of a plug-in module with a 230 V alternating voltage supply in a device for connecting external lines fitted with equidistant, adjacent receptacles for plug-in modules. However, this is possible on the left side, and plug-in modules of the same type can be inserted next to each other in any combination.

FIELD OF THE INVENTION
 The present invention relates to an arrangement for coded and uncoded
 plug-in modules as well as a device for connecting external lines using an
 arrangement of this type.
 BACKGROUND INFORMATION
 A device for connecting external lines to a programmable controller, which
 can be linked to the latter for transmitting signals and can be installed
 at any distance from the programmable controller, is described in German
 Patent Application No. 43 23 440 A1. The connecting device makes it
 possible to have a modular layout in which each actuator or sensor
 connection can be provided with one terminal, which, depending on the type
 of connection, can be provided with an electronic module for signal
 matching and conversion. Input and output modules can be mixed in any
 combination. This has an advantageous effect on project planning,
 installation, troubleshooting, and upgrading of the electronic device. The
 connecting device simultaneously functions as a support unit for the
 electronic modules, which are designed in the form of plug-in modules, and
 has a plurality of equidistant, adjacent receptacles of the same type for
 those modules. Supply and signal lines are routed to the electronic
 modules via a connector attached to the receptacle. Each electronic module
 contains a signal matching circuit for the signals of a signal channel
 supplied on the external lines. Connecting elements for connecting
 external lines are attached with the same spacing as the receptacles and
 are assigned to the latter.
 SUMMARY
 An object of the present invention is to provide an arrangement for coded
 and uncoded plug-in modules which makes it possible, in the case of two
 types of plug-in modules that can be connected next to any plug-in module
 of the same type in equidistant, adjacent receptacles, to prevent a
 plug-in module of one type from being inserted into a directly adjacent
 receptacle on one side of a plug-in module of the other type. A second
 object is to provide a device for connecting external lines, achieving a
 higher packing density while simultaneously meeting the minimum creepage
 distance requirements.
 The present invention has the advantage that it doubles the packing density
 when using electronic modules with low operating voltages. At the same
 time, electronic modules with a low operating voltage can be mixed with
 electronic modules having a higher operating voltage in the same support
 unit without exceeding the required minimum creepage distances in each
 case. For this purpose, the new plug-in module establishes a specific,
 mandatory mounting sequence which cannot be altered by the user. This
 makes the arrangement considerably more fail-safe.

DETAILED DESCRIPTION
 The support unit illustrated in FIG. 1 is a device for connecting external
 lines to a programmable controller. The external lines, which lead, for
 example, to sensors or actuators in a process to be controlled, are
 connected in the lower portion of the electronic device, e.g., to
 connecting elements 1 to 10, which are designed in the form of terminals
 with actuating openings located above them. In the upper portion of the
 device are arranged receptacles 11 to 18 for electronic modules that
 contain a signal matching circuit and perform a signal preprocessing
 operation, which can vary according to the type of external line. Data is
 transmitted to the programmable controller exclusively via a digital
 interface 19, with a digital signal being provided in each of its
 channels. Two vertically arranged terminals are needed for one signal
 channel. One electronic module with a 24 V direct voltage supply can
 control two signal channels. For example, if a 24 V module is inserted
 into receptacle 11, a slide switch 20 is placed in position "DC", and
 external lines for 24 V sensors or actuators can be connected to a first
 signal channel via terminals 1 and 2 as well as to a second signal channel
 via terminals 3 and 4. In the case of electronic modules with a 230 V
 alternating voltage supply, only one signal channel is controlled, which,
 in this case, is routed to the terminal pair on the right. For receptacle
 11, these are terminals 1 and 2. If a 230 V module is inserted, slide
 switch 20 must be placed in position "AC". For lines that are connected to
 a 230 V module, the minimum creepage distance must be greater than 5.5 mm.
 To meet this requirement, it is necessary to ensure that the terminals
 adjacent to the terminals of the signal channel of an AC module remain
 unassigned. For example, if a 230 V module is inserted into receptacle 12,
 terminals 5 and 6 are used for wiring its signal channel. Terminals 7 and
 8 automatically remain unassigned, since they are provided for the module
 in receptacle 12, which does not have a second signal channel in this
 configuration. However, it is important that terminals 3 and 4 also remain
 free. This means that a 24 V module designed for two signal channels
 should not be inserted immediately to the right of a 230 V module,
 although a one-channel 230 V module can be inserted here. This is
 prevented by the coding on the housing of the electronic modules, which
 are also referred to as plug-in modules. Any module can then be inserted
 into receptacle 13, since terminals 7 and 8 are, after all, not assigned.
 FIG. 2 shows a perspective view and FIG. 3 a side view of an uncoded
 plug-in module. The same reference numbers are used for the same
 components. Housing 21 extends across more or less the entire width of a
 receptacle array, which measures 10:16 mm. Housing 21 contains a printed
 board assembly 22, which projects laterally over housing 21 on the side
 where it is inserted into slots in the support unit. For insertion into
 the support unit illustrated in FIG. 1, the modules are suspended from the
 upper edge of the support unit by pivot pins 23 and 24 and swiveled
 downward so that the side edges of p.c. board 22 form a plug connection
 with contact springs in the slots via the contact surface located on the
 upper side of the board. In order for an electronic module designed for a
 direct voltage supply to be inserted into only one receptacle wired for
 this purpose, the side edge is provided with a recess 26 which corresponds
 to the position of pin 25 (FIG. 1) when coding switch 20 is in the "DC"
 position. The uncoded modules illustrated in FIGS. 2 and 3 are used for
 electronic modules with 24 V direct voltage supply and can be inserted
 side-by-side in any combination into receptacles 11 to 18 (FIG. 1).
 As illustrated in FIGS. 4 and 5, housing 27 of a coded module has a
 projection 28 for coding on one side and a recess 29 corresponding to the
 projection of an adjacent, coded plug-in module on the other side, so that
 coded modules can also be inserted side-by-side in any combination into
 receptacles 11 to 18. The coding is provided in the form of a variation in
 the width of pivot pins 30 and 31, thus preventing an uncoded module from
 being inserted into the swivel joint directly to the right of a coded
 module. This minimizes the forces acting on the coding pins, essentially
 avoiding damage to both the support unit and the plug-in modules during
 coding. In the immediate vicinity of a coded module, therefore, only
 another coded plug-in module can be inserted on the right side, while
 either an uncoded or a coded plug-in module can be inserted on the left.
 In a device for connecting external lines, the coding thus reliably
 ensures that the required minimum creepage distance for 230 V modules is
 not exceeded.
 Although the embodiment of the present invention is described on the basis
 of a device in the form of a support unit for connecting external lines as
 well as conversion modules in the form of electronic modules for the
 receptacles in the support unit, the present invention is also suitable
 for any other type of support unit to code plug-in modules. For example,
 it can be used to code plug-in modules in a subrack or front connectors on
 a programmable controller equipped with input or output modules.