SIMULATOR MODULES AND RACK ASSEMBLY

Abstract: A modular input/output arrangement for a programmable controller. The rack assembly of the invention permits selected plug-in input/output modules to interconnect the system being controlled and the processor of the controller. The invention also provides input and output simulator modules which may be plugged into the rack assembly to test operation of the system.

Description: Simulator Modules and. Rack Assembly - \ - This invention concerns improvements in or relating to programmable controllers. A programmable controller normally comprises a central processor unit, an input section which receives 5 signals from the system being controlled, converts these signals to suitable logic signals and passes these logic signals to the processor unit, and an output section for receiving logic signals from the processor unit and passing control signals of a 10 suitable level to the system. It is desirable that a simulator facility be provided for training purposes and for checking programmes stored in the processor unit. v Hitherto, one method of providing a simulator 15 facility has been to connect switches directly to all the channels of the input section and to connect indicator lights dir.ectly to all the channels of the output section. Clearly, this requires that the switches and indicators can operate at the voltages 20 for which the input and output sections were originally designed. Also, such a method requires removing all of the connections from the input and output sections to the system with a resultant increase in down-time of the controller and the system. . 25 In another method hitherto proposed, a simulator box is provided containing switches and indicators and also including a communication interface which allows the box to be connected directly to the processor unit. VThilst this permits the same switches and 30 indicators to be used with any system, the provision of a communication interface in each box is expensive. It is an object of the present invention - X - a simulator facility at relatively lo cost, the implementation of which does not involve unacceptable down-time of the system and controller. It is also an object of the present invention to provide an input/output rack assembly for a programmable controller adapted to receive any desired combination of plug-in modules. According to one aspect of the present invention there is provided an input simulator module for a * programmable controller, the input section of which normally includes a plug-in input module, the input simulator module comprising a plug-in unit having a plurality of connector pins adapted to engage a socket in the input section of the controller, the plug-in unit including switch means connected to said connector pins so that a desired logic signal may be passed to the processor unit of the controller. According to another aspect of the present inventio there is provided an output ' simulator module for a programmable controller, the output section of which normally includes a plug-in output odule, the output simulator module, comprising a plug-in unit having a plurality of connector pins -adapted to engage a socket in the output section of the controller, the plug-in unit including indicator means connected to said connecto pins and arranged to indicate the condition of a logic signal fed to said socket by the processor unit. Further according to the present invention, there is provided an input/output rack assembly for a programmable controller, the rack assembly comprising a base, a top cover having a plurality of socket stations adapted to receive plug-in input/output modules said socket station being connected to a circuit board, O PI - 3 - first terminal means for connecting said circuit board to the system being controlled, second terminal means for connecting the circuit board to the central processor unit of the controller, said first terminal means and second terminal means being interconnected through plug-in input/output modules received in said sockets. Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Pig. 1 is an elevational view, partly sectioned on the line A-A of Fig. 2, of a plug-in simulator module of the present invention; Fig. 2 is a bottom plan vie of the module of Fig. 1; Fig. 3 is an elevational view of the internal * circuit board of a simulator input module made in accordance with the present invention; Fig. 4 is a circuit diagram of the module of Fig. 3; Fig. 5 is an elevational view of the internal circuit board of an output simulator module made in accordance with the present invention; Fig. 6 is a circuit diagram of the module of Fig. 5; Fig. 7 is a circuit diagram of a plug-in input module for a programmable controller; Fig. 8 is a circuit diagram of a plug-in output module of a programmable controller; Fig. 9 is a top plan view of a rack assembly of the present invention; Fig. 10 is a section taken along the line A-A of Fig. 11 is a plan view of the bottom plate of the rack assembly of the present invention. Referring to the drawings, a plug-in module for a programmable controller comprises a module box 1* having a plurality of output connector pins 2 which can be received in a suitable socket of the input or output sections of a programmable controller. The pins 2 are fixed to a plastics top cover plate " 3. . A printed circuit board 4 (as seen in Figs. 3 and 4) serving to connect the pins 2 with the internal circuitry of the plug-in module, as will be described hereinbelow, is secured to the plate 3 and disposed within the box 1. The module box 1 is provided with captive scre'ws 5 by which it can be secured to the rack assembly of Fig. 9. Figs. 3 and 4 show a simulator input module wherei the pins 2 are interconnected by a pair of toggle switches 10 which partially project from the box 1. Input pins 2 are connected to ground 11 and to logic level.12 voltages and, depending on the positions of the switches 10, a desired logic output can be fed to output pins 2 of the module via lines 13. This logic output is fed to the central processor as an input logic signal. Referring to Figs. 5 and 6, an output simulator module includes a pair of light emitting diodes 20 mounted on the circuit board 4 so as to be visible outside the module box 1. The anodes of the light emitting diodes 20 are connected to a logic voltage level 22 via input pins 2 and the cathodes are connected to output terminal pins 2 of the module through respective resistors 21. These pins receiv ^ JR _. _. ι • • *, ^ ,., , , ( . " O and depending on the logic level received, the light emitting diodes 20 will give an indication of the status of the output logic signals. Fig. 7 illustrates a circuit diagram of one embodiment of a plug-in input module for a programmable controller. The circuit is formed on a printed circuit board 4 of, for example, the module of Fig. 1 and serves to convert the input signal from the system being controlle.d to a logic level which can be handled by the processor unit. The circuitry also serves to suppress any noise from the system. The circuit comprises an odd channel 70 and an even channel 72. Each channel includes an input circuit and an output circuit interconnected by an optical isolator 74. The input circuit includes a rectifier bridge 76, a protective Zener diode 78, and a smoothing capacitor 80 and filter 82. The output circuit includes an output transistor stage 84. Thus the incoming signals are isolated from the outgoing signals. The input filter characteristics and resistance values can be selected to reject spurious voltages, while the output stage 84 provides consistent signals. LED's 86 are provided to give a visual indication of logic levels at all times. Fig. 8 shows a circuit diagram of one embodiment of plug-in output module for a programmable controller. This circuit is also formed on a circuit board 4 and is adapted to receive a logic signal from the processor unit and on receipt of such a signal passes a relatively high level voltage control signal to the system. Fig. 8 illustrates a two-channel system in which each channel has isolation provided by a transformer TFI. The primary of the transformer is O PI /»,,-. WIPO * -_. (# - switched by a transistor TRl in response to the input signal and an enable signal. The secondary of the transformer controls a transistor TR2 which triggers a power triac TRCl connected between line and load. Again, LED's are provided to allow logic levels to be monitored visually. A rack assembly for a programmable controller is illustrated in Figs. 9 and 10 and comprises a plastics moulding 50 having a plurality of socket stations 51 adapted to receive the plug-in modules described hereinabove and illustrated in Fig. 1. The socket stations 51 communicate with a printed circuit board 52 fixed between the moulding 50 and a bottom plate 53 and hel there by suitable screws 54 passing through apertures 55 in the bottom plate and corresponding apertures in the printed circuit board 52. A terminal strip 56 is provided for connecting the circuit board 52 with the system to be controlled- The logic signals from the sockets to the processor and from the processor to- the sockets are fed through a terminal connector 57 on the circuit board 52. The printed circuit board includes integrated circuits (not shown) which form the interface between the input/output sections and the processor unit. O PI ,. WIPO

Claims: CLAIMS 1. An input simulator module for a programmable controller having an input section which normally includes a plug-in input module, the input simulator module comprising a plug-in unit having a plurality of connector pins adapted to engage a socket in the input section of the controller and switch means connected to said connector pins so that a desired logic signal may be passed to a processor unit-of the controller. 2. The module of claim 1,. wherein two of the connector pins are adapted to receive a logic high signal and a ground signal, and the switch means comprises a plurality of two-position switches for connecting said signals to selected other ones of the connector pins-. 3. An output simulator module for a programmable controller having an output section which normally includes a plug-in output module, the output simulator module comprising a plug-in unit having a plurality of connector pins adapted to engage a socket in the output section of the controller and indicator means connected to said connector pins and arranged to indicate the condition of logic signals fed to said socket by a processor unit of the controller. 4. The module of claim 3, in which the indicator means comprises a plurality of light sources each having one terminal connected to one of the connector pins for connection to a logic voltage level and another terminal connected to a respective connector pin for connection to respective output logic signals from the processor unit. 5. The module of claim 4, in which each light - * - source is a light-emitting diode, and a respective resistor is connected in series with each light- emitting diode. 6. The module of any preceding claim, in which the plug-in unit comprises a box-shaped housing having the connector pins mounted on a plastics top plate thereof. 7. The module of claim 6, including a circuit board secured to said top plate and disposed within said housing, the indicator means or switch means being mounted on the circuit board to partially project through the housing. 8. An input/output rack assembly for a programmable controller, the assembly comprising a base, a top cover having a plurality of socket stations adapted to receive plug-in input/outpu .modules, a circuit board to which said socket stations are connected, first terminal means for connecting the circuit board to a system' being controlled, and second terminal means for connecting the circuit board to a central processor unit of the controller, _.said first terminal means and said second terminal means being interconnect in use, through plug-in input/output modules received in said sockets. 9. The assembly of claim 8, in which the circuit board is secured between the base and the top cover. 10. The assembly of claim 9, in which the first terminal means is mounted on the cover and the second terminal means is mounted on the circuit board. O PI WIPO

Inventors: CLARKE G
Applicants: CLARKE G, SQUARED CO
Application year: 1979
Main classification: G05B19
IPC codes: C10G1, G05B19, G05B23