GB2292485A - Interface adaptor for communications - Google Patents

Abstract

An adaptor has plural input connectors 1, 4, 5 and plural output connectors 2, 3 and is capable of routing a signal from an input connector to be available for output in serial null modem fashion or in parallel. The adaptor may further include a parallel null modem connection and be encased in a single housing. Input at connector 1 is routed directly to output connector 3 and through the serial null modem connection to output connectors 2. Input at connector 4 is routed straight to connector 2 and through the serial null modem connection to connector 3. Input to connector 5 is routed through the parallel null modem connection to connector 3. Connectors 1 and 2 may be 9-way and connectors 3, 4 and 5 may be 25-way. <IMAGE>

Description

COMMUNICATIONS INTERFACE ADAPTOR The invention relates to a communications interface adaptor.

There is a frequent need to connect items of electronic equipment together, such as a personal computer and a laptop computer, in order to transfer data between them, or to connect a peripheral, such as a mouse, to a computer.

Apart from special networks, communication is normally effected via, but not limited to, 8 bit parallel (or LPT) ports using 25 way D connectors, or RS232 serial (or COM) ports using either 25 way or 9 way D connectors. In either case, a 'null modem' is required which crosses over transmit and receive, and various control lines.

Due to the large number of permutations between protocols and types of connector, at least 6 different cables or adaptors would be required to cover all the possible combinations.

The invention makes it possible to cope with these combinations using only standard straight-through female to female, or extension (male to female) cables.

The invention comprises a communications interface adaptor providing a plurality of communications interface functions and consisting of a serial null modem which has a variety of connector types at each node, combined with the necessary interface to allow communication between parallel ports.

The invention conveniently comprises a circuit board fitted with components and connectors which allow it to connect with or between various combinations of cables or equipment, either for direct connection, or via a 'null modem' configuration. It performs the 'null modem' cross-over function for both serial and parallel communications protocols.

The shape is designed so as to allow direct connection to a variety of equipment types without interfering with adjacent connectors and, to this end, some of the connectors may be mounted via short lengths of cable.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 shows the physical shape and a functional diagram of an adaptor configured for LPT and COM ports of IBM or compatible personal computers, Figure 2 shows the schematic diagram, Figure 3 shows various uses.

Fig. 3(a) shows an application as a general purpose RS232 adaptor between the 25 way socket 4 and the 9 way plug 2. Fig. 2 shows the conventional wiring between the two connectors.

Fig. 3(b) shows an application as a general purpose RS232 adaptor between the 9 way socket 1 and the 25 way plug 3. Fig. 2 shows the conventional wiring between the two connectors.

Fig. 3(c) shows an application of the adaptor as a null modem between the 25 way socket 4 and the 25 way plug 3. Fig. 2 shows that three pairs of connections are crossed over between the two connectors, and that two connections are not. It is important for correct operation of some software which would normally work via a true modem (such as CP-COMMUTE), that pin 6 (Data Set Ready) and pin 8 (Data Carrier Detect) are connected together at each station. This function is performed by the resistors R1 and R2 rather than by direct connection for reasons given below.

Fig. 3(d) shows an application of the adaptor as a null modem between the 9 way socket 1 and the 9 way plug 2. Fig. 2 shows that the wiring and the use of R1 and R2 is as above.

Figs. 3(e) and 3(f) show the use of connectors 1 and 3, and 2 and 4 in opposite combinations.

While the adaptor is in use in any of the configurations shown in Figs. 3(c) to 3(f), the otherwise unused connectors may be used to monitor line activity either side of the null modem.

Fig. 3(g) shows an application of the adaptor as a parallel 'null modem'. Here it is required that active output pins 2, 3, 4, 5 and 6 of each station be connected to input pins 15, 13, 12, 10 and 11 of the other. However, in the parallel mode pins 1 to 8 are all outputs, although not all are used. It can be seen from Fig. 2 that, if pins 6 and 8 of connectors 3 and 4 had been connected directly together for the serial null modem function described above, the active output on pin 6 would now be connected to the unused output on pin 8 and the circuit would not work. It is for this reason that pins 6 and 8 are connected by a resistor, so that pin 6 can toggle, albeit with a small extra load, independently from pin 8.

The shape of the example shown in Fig. 1 is designed such that connectors 1, 4 and 5 plug directly into the rear panels of IBM and compatible personal computers. It is important that these aspects of the body shell 6 are no bigger that the flanges of the connectors, and that the orientation of the connectors is as shown by the marks against pin 1. When the adaptor is correctly connected to the computer, only relevant output connectors should be accessible.

Irrelevant connectors face downwards, and would normally be made inaccessible by the work surface on which the computer is standing.

Key to Figures 1 & 2 Drawing Description Ref.

9 way input socket 2 9 way output plug 3 25 way output plug 4 25 way input socket 5 25 way input plug 6 Body shell, enclosing circuit board Table 1.

Typical uses for the Communications Adaptor.

Connect Invention's See Fig. 3A Connect mouse or 25 way to 9 way adaptor (a) 25 way socket to PC other hardware to for general purpose use COM port Invention's 9 way plug Connect Invention's See Fig. 3B Connect modem or 9 way to 25 way adaptor (b) 9 way socket to PC COM serial printer to for general purpose use port Invention's 25 way output plug using standard serial cable Connect Invention's See Fig. 3C Connect PC or Serial null modem for 25 way socket to PC laptop's COM port to use with INTERLNK, (c) COM port Invention's 25 way LAPLINK, XTLINK, CP output plug using COMMUTE, PC standard serial cable ANYWHERE etc Connect Invention's See Fig. 3D Connect PC or Serial null modem for (d) 25 way socket to PC laptop's COM port to use with INTERLNK, COM port Invention's 9 way etc., as above socket using standard extension cable Connect Invention's See Fig. 3E Connect PC or Serial null modem for (e) 9 way socket to PC COM laptop's COM port to use with INTERLNK, port Invention's 25 way etc., as above socket using standard extension cable Connect Invention's See Fig. 3F Connect PC or Serial null modem for (f) 9 way socket to PC COM laptop's COM port to use with INTERLNK, port Invention's 9 way etc., as above plug using standard serial cable Connect Invention's See Fig. 3G Connect PC or Much faster parallel null 25 way LPT input plug laptop's LPT port to modem for use with (g) to PC printer port Invention's 25 way INTERLNK, LAPLINK, output plug using XTLINK, etc.

standard extension cable All Trade marks used in the above are acknowledged.

Claims (9)

1. A communications interface adaptor for connecting items of electronic equipment together in order to transfer data between them or to connect to a peripheral item, the adaptor comprising at least three input plug or socket units and at least two output plug or socket units and at least one serial null modem on a unitary support and so connected with one another by straight through standard serial cables to enable any selected said input unit to be available for general purpose input and output use or the use of any selected one of available serial null modems.

2. An interface adaptor according to Claim 1, in which said three input units include a 9 way unit and two 25 way units in parallel with said two output units, and in which said two output units are respectively a 9 way and a 25 way unit.

3. An interface adaptor according to Claim 2, in which the pins at one of said two 25 way input units are connected in parallel with the pins at said 25 way output unit, the connections in each of three only pairs of these parallel connections being crossed over.

4. An interface adaptor according to Claim 3, in which the pins on the second of said two 25 way input units are connected in parallel to said pins of said 25 way output unit at points between that unit and said crossover locations.

5. An interface adaptor according to Claim 3 and Claim 4, in which two resistors are connected respectively between the connections in one said crossed over pair of connections and pins respectively on said two 9 way units enabling a further form of modem to be fitted.

6. An interface adaptor according to any one of the preceding claims, in which a parallel null modem is connected between one of said input units and one of said output units to provide for comparatively fast operation of an appropriately selected parallel null modem.

7. An interface adaptor according to any one of the preceding claims comprising an encasing body shell presenting said plug and socket units on its outer surface.

8. An interface adaptor substantially as hereinbefore described with reference to Figures 1 and 2 of the accompanying drawings.

9. A method of operating an interface adaptor according to Claim 8 substantially as hereinbefore described with reference to any one of Figures 3(a) to 3(g) of the accompanying drawings.