GB2225886A

GB2225886A - Programmable message display

Info

Publication number: GB2225886A
Application number: GB8924993A
Authority: GB
Inventors: Gary P Strike; Jeffrey L Ross
Original assignee: FMC Corp
Current assignee: FMC Corp
Priority date: 1988-11-10
Filing date: 1989-11-06
Publication date: 1990-06-13
Also published as: JPH02181819A; FR2638878A1; IT8922320A0; NL8902672A; CA2001591A1; DE3937537A1; BR8905744A; GB8924993D0; ES2017326A6; AU4373989A

Description

:2:2 _!5 IL-13 e1 1 A PROGRAMMABLE MESSAGE DISPLAY This invention relates

to an electronic control system, in particular to a programmable electronic display module, or package, for example for presenting pre-programmed messages to an operator of an apparatus or process, which are indicative of any variance in the routine operation of the apparatus, or in the normal steps of the process, in order to inf orm and prompt the operator to take action to correct the situation.

In the control of modern automated machinery, apparatus and processes, it is convenient and often necessary to present messages to an operator which indicate equipment status, indicate fault conditions or prompt the operator to perform other actions. These messages often have to be programmed or customized to the specific machine, apparatus or process being controlled and it may very well be desirable to alter the content of the programmed messages at some point in time to accommodate improvements or changes in the machinery, apparatus or process. A message display which is programmable and is also erasable for changing programs, and one which displays both alphabetical and numerical strings of characters, is suited to many of these applications, and is a useful tool for the operation and control of the apparatus or process.

Currently, available programmable message displays typically require a complex electrical interface, such as a RS232 computer cable, to the host controller. The interface may be an industry standard or priority, serial or parallel specification. The interface often requires a special communications module to be installed in the host controller which adds hardware complexity and expense. On the display itself, the complexity of the interface hardware and connection terminals makes it necessary to use a large display enclosure and associated operator's panel space.

According to the present invention, there is provided an electronic display device for displaying a desired one of various pre-programmed messages, comprising:- 2 a central controller; an addressable electronic memory containing preprogrammed data representing the various messages, the central controller being arranged to generate an enable signal which is supplied to the memory when it is desired to display a message, the central controller also being arranged to generate address signals corresponding to the addresses in the memory of the various messages to be displayed, the address signals being selectively supplied to the memory in combination with the enable signal to cause the data representing the desired message to be read from the memory and sent to the display for showing of the desired message.

The invention may present messages to the operator through an electronic display such as a video display, or a light emitting diode (LED) display, or preferably a liquid crystal display (LCD), or some other state of the art visual display.

The invention may present messages to the operator through the electronic display which are programmed into a removable erasable programmable readonly memory device (EPROM), which is then mounted to a socket on a circuit board in the display device. The messages may be alpha-numeric, e. g. between 64 to 320 messages on two lines with sixteen characters on each line.

Another preferred feature of the invention is to provide the electronic display and memory as a module, or package, which can be used as an auxiliary component of a central processing unit (CPU) or other programmable digital controller based electrical system or a programmable logic chip (PLC) of a host apparatus, which forms the central controller. The module may be panel mounted to a console or to the surface of the host apparatus.

In a preferred form, the invention only requires a simple interface with the controller of one or two signal wires and a common line at a +12 VDC level for a sink mode or at a 0 volt level for a source mode.

Typically, the machine, apparatus or process, which is tc 7 3 be operated and monitored, has an electrical control system which contains the CPU, or PLC or some other type of digital based host controller. The programmable electronic display module is interfaced with the host controller, which has an additional function of selecting the code for a particular programmed message to be displayed.

once the code for the message has been identified in the host controller, then, by means of the simple serial communications wiring, the code is transmitted to the EPROM of the display identifying and retrieving the particular programmed message, which is then displayed on the LCD.

The programmable message display module can be mounted to a console, panel or to the surf ace of the apparatus and is used to display the programmed messages at the request of the CPU, or the PLC, or other host controller.

The display advantageously employs a commercially available low-cost wide angle liquid crystal device in the message output window. It is to be understood that the display may be a video display, or a LED display, or some other state of the art visual display.

The display preferably supports a 128 character ASCII (American Standard Code For Information Interchange) set which includes both alphabetical and numerical characters and shows key words and numbers to inform and prompt the operator to take appropriate action for controlling the operation of the apparatus or process.

Each message is typically 2 lines by 16 characters. Up to 64 messages can be displayed with a 2764 EPROM memory device, and up to 320 messages can be displayed with a 27128 EPROM memory device. Blinking messages, as well as alternating messages, allow up to 64 character messages. The display may be powered for example from any 8 to 15 VDC power supply.

A small terminal strip may be provided at the rear of the display for quick, easy connections of power and signal inputs.

These and other preferred features of the invention will from the dependent claims and from the following be apparent.

4 description of a preferred embodiment taken in conjunction with the drawings wherein:-

Fig. I illustrates the signal and common line connections of the programmable electronic display package to the host controller, and the electrical power connection of the power supply to the programmable electronic display package.

Fig. 2 is a top view of the electronic display package showing the terminal strip; and Fig. 3 is a typical EPROM device.

Fig. 4 is a bottom view of the display package shown in Figure 2 illustrating a schematic of the electronic circuitry; Fig. 5 is an illustration of three wave forms, and Fig. 6 is a simplified flow chart of the program performed by the microprocessor shown in Fig. 4.

The operation of the system and the programmable electronic display 12 will now be explained.

A programmed EPROM 10 is inserted into a vacant twentyeight pin socket (not shown) on a circuit board (not shown) housed in the display module 12. The DC power source module 14 is connected by two electrical wires 15 and 17 to the 12V and GND (Ground) screw terminals 18, 20 of the terminal strip 16. A DC current of approximately 180 milliamperes at 12VDC is required to operate the electronic display. The terminals of the two signal lines EN (enable) 22 and CNT (count) 24 are connected by electrical wires 26, 28 to the output terminals 30, 32 of the host controller 34. The count and enable inputs on the electronic display sink or source at approximately 10 milliamperes of the DC current. A third electrical wire 36 connects the COM (common) terminal 38 on the electronic display terminal strip 16 to common voltage output terminal 40 on the host controller 34.

When the DC power module 14 is turned on, the EPROM 10 delivers an introductory message which is displayed on the LCD 40 for approximately two seconds, and then the EPROM clears the display.

In order to monitor the operation of the apparatus or process, an enabling signal is first received by the host controller 34 from the apparatus or process.A pause off approximately two milliseconds follows the receipt of the enabling signal (Fig. 5). Then a count signal (Fig. 5) between 1 and 320 pulses is sent to a counter in the display package 12. The number of the pulses correspond to the code number of the designated programmed message which is to be displayed on the LCD 40. The counter counts the transmitted pulses and, after a timed preset pause (Fig. 5) following the last pulse of the train of pulses, the total count is transmitted to a comparator which compares the total count with an index of the code numbers of the programmed messages in the memory of the EPROM. The appropriate message is then retrieved from the memory of the EPROM and transmitted to the display window of the LCD 40. The LCD 40 continues to display the message until the enabling signal is turned off resetting the host controller 34.

No delay is required between the enable line and the count line. There is a maximum of 1000 Hz count line toggle rate. The EPROM has an access time of 250 nanoseconds or less.

Figure 6 schematically shows the program executed by microprocessor 10. Upon activation of power module 14 and after briefly causing display of the introductory message, microprocessor 14 starts to monitor signals from the CPU of the host controller 34. When the enable signal is received over wire 26, microprocessor 10 clears the display 40 and resets a code pulse counter to zero. Code pulses received over wire 28 are then counted by the pulse counter. A determination of the message address then is made from the count total by means of the comparator. If no address is found, the program loops back to continue monitoring the signals from the CPU. When an address is found, the corresponding data is read from the memory and sent to the LCD display. The corresponding message continues to be displayed whilst the enable signal is present; otherwise the program loops back to monitor signals from the CPU.

A modification of the programmable electronic display system described above can send both enable and count signals over the same line. An enable/count signal line held logic 6 low level for preset time (TR Fig. 5) causes the programmable electronic display circuitry to disable and clear its display. Any deviation from logic low level is considered a count pulse on the leading edge of transition from logic low to logic high level. An enable/count signal remaining at logic high level more than the preset time (TF Fig. 5) indicates that the total count corresponding to the address of the message programmed into the memory has been received and the message should be indexed from the EPROM and displayed. of course, a logic high f or a preset time could be used to initiate counting and a logic low f or a preset time could be used to indicate end of count instead. In summary, one of the advantages of the system and the programmable electronic display module is that a costly parallel signal interface or a complex RS- 232/ASCII serial interface is not required. Another advantage is that the Programmable message controller with alphabetical and numerical display requires only two signals to transmit the message selection data, i.e.

the enable signal which allows the message controller to start looking for the address signal, for example by counting pulses on the count signal input line; and the address signal, for example a count signal which contains the actual message number as a simple serial string of pulses, for example five pulses represents message five, ten pulses represents message ten and so on.

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Claims

1. An electronic display device for displaying a desired one of various pre-programmed messages, comprising:a central controller; an addressable electronic memory containing preprogrammed data representing the various messages, and a display for showing said messages; the central controller being arranged to generate an enable signal which is supplied to the memory when it is desired to display a message, the central controller also being arranged to generate address signals corresponding to the addresses in the memory of the various messages to be displayed, the address signals being selectively supplied to the memory in combination with the enable signal to cause the data representing the desired message to be read from the memory and sent to the display for showing of the desired message.

2. A display device as claimed in claim 1 wherein the address signal comprises a number of pulses which are counted by the memory in order to determine the address of the desired message.

3. A display device as claimed in claim 1 or 2 wherein the memory is connected to the central controller by a first path for transmitting the enable signal and a second path for transmitting the address signals.

4. A display device as claimed in claim 3 wherein no delay is required between the enable and count signals.

5. A display device as claimed in claim 1 or 2 wherein the memory means is connected to the central controller by a common path over which both the enable signal and the selected address signal are supplied sequentially to the memory means.

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6. A display device as claimed in claim 5 wherein the enable signal is generated by holding the signal path at a logic low or high level for a predetermined time, whereafter the display is cleared and the memory is readied f or reception of the address signal; and the signal path is held at a logic high or low level respectively upon transmission of the address signal to initiate showing of the desired message.

7. A display device as claimed in any of claims 3 - 6 wherein the path or paths are electrical connections and a common power line is provided for the display device.

8. A display device as claimed in any preceding claim wherein the memory comprises an erasable programmable readonly memory device.

9. A display device as claimed in claim 8 wherein the memory can hold from between 64 and 320 messages.

10. A display device as claimed in any preceding claim wherein the display is a wide angle liquid crystal display capable of supporting a set of 128 ASCII characters.

11. A display device as claimed in any preceding claim wherein the memory and display are contained in a modular housing connected to the central controller, which is housed in a host apparatus.

12. A display device substantially as described with reference to or as shown by the accompanying drawings.

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