GB2290440A

GB2290440A - Mains borne signalling system

Info

Publication number: GB2290440A
Application number: GB9512343A
Authority: GB
Inventors: Paul Telco
Original assignee: ELECTROBOSS Ltd
Current assignee: ELECTROBOSS Ltd
Priority date: 1994-06-16
Filing date: 1995-06-16
Publication date: 1995-12-20
Also published as: GB9412072D0; GB9512343D0

Abstract

A system comprises a controlling transmitter and one or more interactive receivers, which stations communicate with one another via the mains cabling. On installation, the controlling transmitter monitors any signals already present on the mains to check which system codes, if any, have already been allocated to other systems within range of the system. As a result of this monitoring, the controlling transmitter allocates an unused system code for the system. Thereafter, each receiver is provided with this system code and a channel code associated with that receiver. An additional feature of the present system is that collisions at the time of installation are prevented as a result of the controlling transmitter checking for the presence of any other programming codes before transmitting a programming code itself.

Description

MAINS BORNE SIGNALLING SYSTEM This invention relates to mains borne signalling systems and in particular relates to the coding of stations which can communicate via such a system. In mains borne signalling systems a number of stations can communicate with each other via the mains cabling which is used for signal transmission. Such systems are broadcast type systems and hence it is usually necessary to provide some form of selectivity particularly when multiple systems are in operation. This is to enable signals to be routed to the appropriate stations.

There is a European standard for mains signalling which provides only one frequency band for open multiple access and the requirements for its use are such that selection has to be based on coding within the data transmitted. For example coding is used to distinguish a) between otherwise identical systems operating within range of each other, b) between different target receivers within the system, and c) between different systems.

The conventional arrangement for meeting these requirements is to provide each station on the system with a number of switches which can be set by an installing engineer. The installing engineer selects a suitable system code, thereafter selecting an additional channel code for each receiver.

In practice this adds to the cost of the equipment and calls for a certain amount of technical skill from the installer. In particular the construction of the equipment is complicated by the need to provide access to the circuitry, whilst at the same time complying with the relevant electrical safety requirements.

It is an object of the present invention to provide a solution to some or all of the above problems.

According to a first aspect of the present invention there is provided a method of allocating codes in a mains borne signalling system which comprises using a controlling transmitter to identify and store an available system code, transmitting a programming code including the system code from the transmitter to the receiving stations which make up the system and then providing the receivers with a code or codes indicative of the channel with which the receiver or receivers is associated.

This has the advantage that the installation can be carried out by a householder or other unskilled person.

The only decisions that person need make are which receivers should be grouped together in each channel.

Advantageously, if a programming code originating from another transmitter is present in the signals on the mains at the time when it is intended to transmit the programming code, then the transmission is aborted and a fault is indicated to the installer.

Two types of receiving station may be used in conjunction with the method of the present invention.

In the first type of receiver, the channel code to be associated with that receiver is entered via a user interface at the receiver. This has the advantage that any such receiver can be connected to the mains (possibly simply by switching it on) before the programming code is transmitted. The receiver may be arranged so that the channel code is to be entered before, while or after the transmission of the programming code from the transmitter.

In the second type of receiving station, the channel codes are provided to the receivers by way of a transmission from the controlling transmitter. In this case, the installer connects all the receivers to be associated with a given channel to the mains and then enters the desired channel number of the controlling transmitter. This has the advantage that the channel code is programmed automatically into any such receivers in the system.

A system according to the present invention may have receivers exclusively of one of the above types or may comprise a combination of the two types.

Preferably, with regard to those receivers having a user interface, the channel code is entered by means of a keypad. This has the advantage that the need for dual-in-line switches is obviated.

According to second aspect of the present invention there is provided a controlling transmitter comprising: means for connecting the transmitter to the mains cabling; means for monitoring any signals present on the mains cabling; means for establishing an available system code as a result of said monitoring; means for storing said system code; and, means for transmitting a programming code comprising said system code via the mains cabling to one or more receiving stations.

This has the advantage that the problems involved in allocating an available system code and setting switches on each of the receivers in accordance with the system code are solved.

According to a third aspect of the present invention, the controlling transmitter comprises a means for inputting a channel code, said channel code being included in said programming code.

Advantageously, said programming code further comprises a write code and said controlling transmitter further comprises means for detecting the presence of a write code in the signals on the mains cabling and mms for aborting the transmission of said programming code and reporting a fault if a write code is detected.

This has the advantage that problems caused by interference with the programming codes being transmitted by another controlling transmitter are avoided.

According to a fourth aspect of the present invention there is provided a mains borne signalling system in which a plurality of stations can communicate by way of mains cabling, said stations comprising: a controlling transmitter according to the second aspect of the present invention; and, a receiving station comprising: input means enabling the user to input a channel code to be associated with that station; and, a memory means for storing said channel code.

According to a fifth aspect of the present invention there is provided a mains borne signalling system in which a plurality of systems can communicate by mains cabling, said stations comprising: a controlling transmitter according to the third aspect of the present invention; and a receiving station comprising: means for inputting said system code transmitted via the mains cabling; and a memory means for storing said channel code.

A sixth aspect of the invention provides a mains borne signalling system in which a plurality of stations can communicate by way of mains cabling, one of these stations being designated a control transmitter and being operable to identify an available system code and to transmit that code to the receiving stations making up each system.

Typically the codes will be stored in a suitable non-volatile memory such as an EEPROM or a battery backed RAM.

Particular embodiments of the present invention will now be described in more detail by way of example only.

In a first embodiment of the present invention there are a number of stations that can communicate with each other by way of mains cabling. These stations comprise a number of receiving stations and at least one controlling transmitter. In this embodiment the controlling transmitter is used to assign codes to the receivers which make up the or each system and to enable those receivers to receive the messages which are intended for them. Each station has some form of processing facility including a non-volatile memory for recording codes.

As mentioned the selection and allocation of codes is performed from the controlling transmitter. This transmitter is provided with a keypad and an LCD display.

In use the transmitter initially is prompted to listen to the traffic on the mains cabling to enable it to record any compatible system code numbers which it detects and following this to assign to itself a suitable system code from an available range. This code must not be one of those which it has detected as being in use.

The code selected is then written into the non-volatile memory of the transmitter which can be an EEPROM or a battery backed RAM. Any other form of permanent memory could also be used.

To establish the channel codes which are to be allocated to the receivers, only the receivers that are to respond, for example to channel 1, are initially connected to the mains cabling, perhaps simply by switching them on. The controlling transmitter is then prompted to transmit a programming code which comprises a write code, the system code which has been selected and the channel code for that group of receivers.

The or each receiver on receiving the programming code (which may be transmitted more than once for confirmation) writes the system and channel code numbers into its own non-volatile memory. The receiver also writes into the memory a flag which is to inhibit future attempts to set codes unless preceded by a special reset code.

This procedure is then carried out for the next group of receivers which may be identified as channel 2 and the controlling transmitter again transmits the programming code which comprises the write code, the system code and the selected channel number.

As noted above, in the first embodiment, the programming code includes a write code. Having monitored the signals on the mains cabling and allocated itself an available system code, the controlling transmitter then checks the signals on the main cabling to establish whether a write code is present. The presence of such a write code indicates that a similar system, sufficiently close to the present system, is transmitting a potentially interfering programming code onto the mains. In this circumstance, the controlling transmitter of the first embodiment aborts the transmission of its programming code and outputs an error message via its LCD display.

In this way all the receivers can be programmed without any intervention with the circuitry and thereby electrical safety is maintained. Furthermore, the problems of the prior art of setting dual in line switches are avoided.

A more advanced implementation is possible if one or more of the receivers is provided with keypads and a display to enable a user to input commands and data at the receiver. In this case such receivers can be connected and set to their chosen channel codes before, while or after the controlling transmitter transmits the programming code to write the system code into a permanent memory.

A second embodiment of the present invention is a hybrid mains borne signalling system comprising a controlling transmitter and a plurality of receiving stations. The receiving stations comprise one or more interactive receivers, and also one or more dumb receivers which do not have a user interface.

At the time of installing the system, any interactive receivers with keypads are connected to receive signals from the mains. The dumb receivers to be classified into a first channel are also connected to the mains. Thereafter, the programming code (which comprises a write code, a system code and channel codes for the connected dumb receivers) is transmitted by the controlling transmitter. At this time, by operating the keypad of each of the interactive receivers, the person installing the system can select whether to store the system code provided at that receiver or whether to ignore the transmission altogether. It might be necessary to ignore the system code altogether if the receiver is not intended to belong to the same system as the controlling transmitter.

If, however, it is decided to store the system code supplied by the transmitter then an appropriate key can be pressed to cause the code to be stored. Thereafter, the installer has the choice of either setting operating characteristics of the receiver, or alternatively unlocking that receiver from the controlling transmitter.

In the course of setting the operating characteristics of the interactive receiver, the installer may input the channel code to be associated with that receiver via the keypad, and also define whether input to the keypad can override commands received from the controlling transmitter.

If, however, the installer presses the key which results in the interactive receiver being unlocked from the transmitter, then both the system code and the channel code will be set to zero. This has the result that the receiver operates independently of the controlling transmitter.

The channel codes for the dumb receivers are set as described in relation to the first embodiment.

The programming code of the second embodiment also comprises a write code and prevents interference between two systems at the time of initialization in the same way as described in relation to the first embodiment.

Additional codes can be inserted into the channel data and this could provide a facility to define user's rights as in network practice. For example, the possibility of defining the extent to which received instructions may be overridden by local keypad input.

In order to change a code which has already been assigned a procedure which is in effect the reverse of the above assignment procedure is carried out.

Claims

1. A method of allocating codes in a mains borne signalling system having a controlling transmitter and one or more receiving stations, said method comprising the steps of: using the controlling transmitter to identify and store an available system code; using the controlling transmitter to transmit a programming code which includes said system code via said mains cabling to said receiving stations; providing said receiving stations with a channel code which indicates which channel the receiving station is associated with.

2. A method according to claim 1 wherein said channel code providing step comprises: using the controlling transmitter to transmit a programming code which further comprises said channel code.

3. A method according to claim 1 wherein said channel code providing step comprises entering the channel code via a user interface at said receiver station.

;

4. A method according to claim 1 further comprising the step of using the controlling transmitter to confirm the absence of a programming code in the signals on the mains cabling before beginning transmission of the programming code.

5. A controlling transmitter for use in a mains borne signalling system in which plurality of stations can communicate by mains cabling, said transmitter comprising: means for connecting said transmitter to said mains cabling; means for monitoring the signals on said mains cabling; means for identifying an available system code in accordance with the results of said monitoring; means for storing said system code; means for transmitting a programming code including said system code via the mains cabling to one or more receiving stations.

6. A controlling transmitter according to claim 5 further comprising: a user input means for inputting a channel code; a memory means for storing said channel code input by the user.

7. A controlling transmitter according to claim 5 or 6 wherein said programming code further comprises a write code, and said transmitter further comprises: means for checking for the presence of a write code output by another transmitter onto the mains cabling; and means for aborting the transmission of the programming code if a write code is present; and means for reporting a fault to the user if such a write code is present.

8. A mains borne signalling system in which a plurality of stations can communicate by way of mains cabling, said system comprising: a controlling transmitter according to claim 5; one or more receiving stations comprising a means enabling the user to input a channel code associated with that receiver and memory means for storing said channel code.

9. A mains borne signalling system in which a plurality of stations can communicate by way of mains cabling, said system comprising: a controlling transmitter according to claim 6; one or more receiving stations comprising a means for inputting said system code transmitted via said mains cabling and memory means for storing said system code.

10. A mains borne signalling system substantially as hereinbefore described.

11. A controlling transmitter substantially as hereinbefore described.

12. A method of allocating codes substantially as hereinbefore described.