GB2074422A - Numerical communication monitoring device - Google Patents

Abstract

A self-contained numerical communication monitoring device for checking serial data transmissions comprises a casing having a front panel with a non-cathodic visual display mounted thereon. A switch is provided on the panel for selecting a plurality of different modes of operation of the device and/or for controlling automatic transcoding by preliminary display of a label relating to the data. The device is operable to monitor transmissions in accordance with the standard ARINC 429, and/or other codes, so that the display provides an indication, in clear, of the complete state of a transmitted data item. <IMAGE>

Description

SPECIFICATION Numerical communication monitoring device This invention relates to a miniature numerical connection monitoring device for monitoring transmissions of digital information.

Numerical connection monitoring devices are known which include the circuitry and visual display necessary for monitoring information transmitted in accordance with a pre-established convention. In general, these known monitoring devices comprise two parts, namely a visual display, and circuitry for analysis and synthesis of the information flowing along the transmission line with the display of morphological and temporal characteristics.

If they are able to monitor a multiplicity of standards, these monitoring devices are usually large and heavy, are not self-contained, and cannot be carried in one hand, which renders difficult and costly the operation of monitoring the operation of equipment, especially aircraft equipment, sensors having digital outputs, and numerical connections between sensors and instruments.

An object of the present invention is to provide a small, portable, self-contained monitoring device of a new generation, suitable for monitoring a transmission which is being carried out according to a particular standard previously defined, for example the ARINC 429 standard.

Preferably the device comprises a small casing with a display of 7-segment devices on its front face which displays, in a directly intelligible format, data flowing along a numerical bus.

The putting into service, in years to come, of aircraft equipped with sensors having digital outputs, and having numerical connections between sensors and instruments, will require considerable alteration of the devices for checking and examination of data connections. The miniature, portable, self-contained monitoring device which is the subject of this invention will answer this need. Being of a small bulk which may be held in only one hand, it enables the display, in an entirely decoded form, of all of the morphological and temporal characteristics of the data flowing along a numerical transmission line.

The monitoring device in accordance with the present invention checks series transmissions of 32 bits which are transmitted in accordance with the standard ARINC 429-MARK 33 Digital Information Transfer System (DITS). The device preferably displays the data entirely decoded in an easily-readable fashion on a liquid crystal display (LCD) with 8 large digits.

The apparatus therefore enables the user to choose, by simply operating a rotary switch, any one of the following displays: -information entirely decoded in the unit provided by the ARINC with automatic positioning of the decimal point, whether the data is expressed in binary code or in binary-coded decimal (BCD). For example, a heading will be displayed in degrees, for example in the form:- 11 5.66 -a message in hexadecimal form without decoding of the information. The above heading is then displayed as: H F5B800 -a display of the matrix code (MC) and of the source destination identifier (SDI) -period for renewal of a message (in milliseconds and tenths of a ms.) The parity of a message may be checked.

Although the invention is described in relation to the recognition of data flowing along a numerical connection in the ARINC 429 format, it can be used for subsequent developments of encoding format and of speed which may occur.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a front elevation of a monitoring device in accordance with the invention, Figures 2a and 2b illustrate the transmission of data in accordance with the ARINC 429 standard, Figure 3 illustrates the sixteen alphanumeric states in a hexadecimal code, Figure 4 illustrates use of a display in relation to label data, Figure 5 illustrates the displaying of certain data items, and Figure 6 is a block schematic diagram of the monitoring device.

Referring to Fig. 1 of the drawings, on a front panel of a monitoring device in accordance with the invention there is provided means to select an item of information by designation of its ARINC 429 label, in accordance with specification 429-3 of 1 5th December, 1979. The designation of the label is set by three coding wheels each having eight positions, numbered from 0 to 7, which enable an octal display of 256 different positions to be provided. A knob for selection of the mode of display enables selection of the information which it is desired to display by choosing from four switch positions. A two-position frequency selector allows a choice of the desired transmission frequency for the information. An 8-element display allows the presentation of conventional numerical or alphanumerical data relating to the state of reception of the data.

The monitoring apparatus, although small and light, enables presentation in a clear and concise fashion, and in a large format, of all of the information which characterises the data flowing in a numerical bus ARINC 429 format. The means for presenting the information and the mode selection means are contained in a casing, the main dimensions of which may be, for example, 150 X 80 X 50 (mm).

The four modes of operating the display will now be described.

The first mode is illustrated in Figs. 2a and 2b. In this mode the display device shows the value of the information, expressed in decimal code in up to seven digits plus a sign, in the unit of expression provided by the ARINC 429 as a function of the label chosen out of the 256 possible combinations by means of the three octal coding wheels. This first mode will be better understood from the description of a particular case.Let us assume that it is required to check the value of the heading information being transmitted in ARINC 429 format over a two-wire transmission line, and that the information being transmitted is representative of an angle of 112.5t. Figs. 2a and 2b show synoptically and temporally the way in which the information is represented: in ARINC 429 form the states 1, 0, - 1 correspond to values of voltages given by the ARINC standard (Fig. 2a). By means which will be described later, the data is extracted in a binary form in which two successive 1 states are represented by a double-length pulse as illustrated in Fig. 2b.

The binary information is coded in a mode of fractional representation in which the presence of binary moments is representative of a fraction of the maximum displayable for one given item of information. Thus, for angular information, the maximum displayable is + 180 and each binary moment, starting from the left, represents a fraction of 180 . The final value is obtained by addition of all of the fractions of 180 . The mode of display carries out all of the transformations described previously and gives the value of the data in decimal representation.

In this example the device will display 112.5 . It must be observed that in this mode the information is expressed automatically in the unit corresponding to the label chosen.

As soon as the label has been indicated on the three coding wheels, the monitoring device carries out transcoding of the information and effects the necessary encoding of the information the state of which is required to be known. This transcoding is made possible by the relationship which exists between the octal label and the representation unit. This relationship has been set up by the ARINC committee for more than 200 labels. The device has an internal store which is capable of retaining these relationships and which can easily be adapted to new particular uses which might be set up in future.

In the second mode of visual display, the information is not transcoded as in the preceding mode, but whatever octal label is chosen is expressed in a mode of hexadecimal representation with 6 alphanumerical characters, the 16 possible states of which are shown in Fig. 3. In order to avoid errors of interpretation between these modes, hereinafter referred to as MODES 1 and 2, respectively, MODE 2 is called to mind in the display by a letter H appearing permanently at the character position furthest to the left, as soon as MODE 2 is selected.

If the device is set to work in MODE 1, automatic setting of the display into MODE 2 is effected if the input information is not recognised in consequence of non-assignment of the chosen label.

In MODE 3, the display gives status data associated with the label in question. The status data are of an essentially discrete nature and consists of two groups of two bits surrounding the main data as indicated in Fig. 4.

The left hand data consist of a 4-value code, the significance of which is as follows: Binary code 0O represents F/W Failure warning " '' 01 '' NCD No computed data " '' 10 '' TEST Test 11 " 11 '' NO Normal operation The right hand group expresses, in the present state of definition, the number of the sensor sending out the data, with the following significance: Binary code 0O represents SensorO '' '' " " 1 " '' 10 '' '' 2 " ,, 11 '' '' 3 One of the characteristics of the present invention which is not obvious is that of providing a device which displays in clear (i.e. in normal language) the sensor state information. That is why the display is divided into two independent portions, each having four information characters.

In accordance with the preferred embodiment of the invention, the front face of the casing (Fig. 1) carries, engraved in abbreviated form on its left hand side, the four states which correspond with the left hand group described above. They are positioned so as to be read in combination with the first four digits of the display device, and the states of the right hand group described above by employing the right hand portion of the display device. The device indicates the states corresponding to the positions of the left hand and right hand groups by the appearance on the display device of two dashes, one per group, opposite the corresponding engraving, as shown in Fig. 4.

For the three preceding modes there are provided two other types of display which consist of writing, according to the method of writing given in Fig. 5, the words "LABEL" and "BUS".

The word "LABEL" is displayed when the label chosen by the setting of the coding wheels has not been received by the device. The word "BUS" is displayed when no message has been received by the device, especially when the transmission line has been cut off and/or the transmission has been interrupted.

In a fourth mode (MODE 4) the apparatus records the validity of the information chosen by the three octal coding wheels and its temporal renewal characteristics. It enables, firstly, the writing of the interval of time which separates two items of information of the same label, expressed in ms (milliseconds) and tenths of ms and, secondly, the writing of the letter P at the left of the display when the number of binary moments of the word of the chosen label, received by the device, is even.

When the renewal interval is longer than two seconds, the apparatus indicates the face by displaying the characters OF, being an abbreviation of the word OVERFLOW.

Referring now to Fig. 6 of the drawings, the device comprises an electronic receiver head circuit a for receiving ARINC information, which circuit carries out the transformation of threeinput signals, received over a two-wire line 1 from a bus, into two-moment binary signals which may be employed directly by a computer unit. The latter comprises a microprocessor b, a work store e, a store d containing a program, and an accurate frequency reference j. Under the control of the program recorded in the store d, all of the data received by the receiver head a are analysed and their labels are compared with that set up on the code wheels n.If the label displayed on the wheels n is recognised, and if the selector knob is set at MODE 1, the processor b interrogates a transcoding store c in order to ascertain the exponent part of the information, then processes the latter and controls a display g through an auxiliary circuit h which enables the necessary signals for the display to be generated.

The casing is connected to the numerical bus by ineans of a flexible lead which is suitable for rapid connection by terminal clamp or plug.

The apparatus is fed from a battery ACC, which may be recharged by a voltage applied to lines m and p. Great independence of operation is rendered possible by the low power consumption demanded by the apparatus.

An interface or level adaptor k is provided, which works in relation to the mode selector.

By numbering one of the three wheels of the- modular unit from 0 to 3 twice separately, a communication monitoring device can be achieved which enables checking of either the ARINC 429 code or of the ARINC 41 9 code, as desired.

Claims (10)

1. A self-contained numerical communication monitoring device for checking serial data transmission, the device comprising a casing having a front panel; a non-cathodic visual display mounted on panel; means on the panel to select the information being transmitted and operable to monitor transmission in accordance with the standard ARINC 429 and/or other codes so that the display provides an indication in clear of the complete state of a transmitted data item; manual selection means for selecting a plurality of different modes of operation of the device and/or for controlling automatic transcoding by preliminary display of a label relating to the data.

2. A monitoring device as claimed in Claim 1, in which the mode of operation of the display is selectable from the modes; numerical value; hexadecimal value; matrix codc source destination identifier; and parity/renewal interval; the parity/renewal interval mode forming a single mode of display simultaneously of two different items of information.

3. A monitoring device as claimed in Claim 2, in which the display of the information is obtained by automatic transcoding of the information as a function of data provided by a displayed label.

4. A monitoring device as claimed in Claim 3, in which the label is an octal label of three digits which are displayed manually by means of three coding wheels each having eight positions.

5. A monitoring device as claimed in Claim 4, in which a mode is provided for display of the information as a hexadecimal value, which can either be selected manually or can be selected automatically if a label has-not been assigned, the mode being indicated on the display by the appearance of a particular character conjointly with the hexadecimal data displayed.

6. A monitoring device as claimed in Claim 5, in which designation of the mode of display of the discrete information from the ARINC (MC-SDI) word, which are associated with its decoded value comprises the appearance on the display of two dashes, one for a group of designations FW-NCD-TEST-NO; and one for a group of designations 0-1-2-3.

7. A monitoring device as claimed in any preceding claim, in which a single mode of display of two different items of information simultaneously provides: a mode of display, in clear, in a right hand portion, of the interval of time separating two items of information of the same label, and the display of a particular character in a left hand portion when the parity of the information being tested is even, so that the display provides a means of checking the parity of the message.

8. A monitoring device as claimed in Claim 4, Claim 5 or Claim 6, including automatic means for indicating a disturbed state of transmission of the information on a transmission bus by displaying the word "BUS" when the device senses a lack of coherent numerical information on the bus, and for displaying the word "LABEL" when the chosen label is not recognised as existing on the transmission bus; and wherein two of the three coding wheels of the modular unit are numbered from 0 to 7 and one wheel is numbered from 0 to 3 twice to enable use of the device for checking either of the codes ARINC 429 or ARINC 41 9.

9. A monitoring device as claimed in Claim 8, wherein the letters OF are automatically displayed when a time interval between two items of information exceeds several times a maximum time of standardised renewal.

10. A monitoring device as claimed in Claim 1 and substantially as hereinbefore described with reference to the accompanying drawings.