WO1991011870A1

WO1991011870A1 - An interface adapter

Info

Publication number: WO1991011870A1
Application number: PCT/US1991/000665
Authority: WO
Inventors: Michael D. Brother; Gerald A. Kammerer; David E. Splitz
Original assignee: Codex Corporation
Priority date: 1990-02-02
Filing date: 1991-01-31
Publication date: 1991-08-08
Also published as: AU7255491A

Abstract

A communications interface adapter (200) for interconnecting supporting equipment having a communications port with external equipment employing an industry standard signaling interface, the interface adapter including a housing (208); a connector adapted to be plugged into the communications port, the connector providing signal paths between the outside and the inside of the housing; and an interface circuit (204) located within the housing and connected to the first connector, the interface circuit adapted to convert logic type signals received from the communications port into signals conforming to the industry standard signaling interface for use by the external equipment.

Description

AN INTERFACE ADAPTER

Background of the Invention The invention relates to interface adapters for interconnecting data communications equipment.

Data communications equipment that exchanges data with other data communications equipment typically employs a set of rules (generally referred to as a data communications interface) that defines the terms of the data exchange. Among other things, the communications interface specifies the electrical characteristics and functions of the signals produced by the equipment, the identity of the lines on which the signals are available and the format of data and control signals. If equipment made by another manufacturer is to communicate with that equipment, it too must employ the same communications interface (or at least a compatible interface) .

To facilitate the interconnection of equipment made by different manufacturers, various standards setting groups, representative of different segments of the industry and of different countries, have established a number of different industry standard communications interfaces. For example, the Electrical Industry Association, in cooperation with the Bell System and certain independent modem manufacturers and computer manufacturers, has developed the RS-232 standard. .And, as another example, the government post, telegraph and telephone authorities of the United Nations, in conjunction with the Comite Consultatif International Telephonique et Telegraphique (CCITT) , have promulgated the V.24 communications interface standard, among others.

As a rule, each manufacturer of data communications equipment employs at least one of the industry standard communications interfaces for the equipment it produces so that its equipment can be used with the equipment of other manufacturers. Since there are numerous industry standards, however, it is often the case that a manufacturer will make different variants of its equipment available, each variant employing a different one of the data communications interfaces. Thus, the purchaser selects the variant that is appropriate for the data communications system to which it will be connected.

Summary of the Invention

In general, in one aspect, the invention is a communications interface adapter for interconnecting supporting equipment having a first communications port with external equipment having a second communications port, the external equipment communicating through the second communications port in accordance with an industry standard signaling interface. The interface adapter includes a first multi-pin connector adapted to plug into the first communications port; an interface circuit connected to the first connector, the interface circuit being adapted to convert logic type signals received from the communications port into signals conforming to the industry standard signaling interface; a second multi-pin connector adapted to plug into the second communications port; and a cable connecting the interface circuit to the second connector for carrying the converted signals to the external equipment.

Preferred embodiments include the following features. The interface circuit is adapted to convert signals received from the external equipment into logic type signals that are sent to the supporting equipment through the first connector. The interface circuit asserts an identification signal on at least one of the pins of the first connector, the identification signal identifying the industry standard signaling interface being implemented by the interface circuit and identifying whether the interface adapter is a DTE type or a DCE type. At least one of the pins within said first connector is dedicated to solely receiving power from the supporting equipment for the interface circuit. The industry standard signaling interface may be any one of the following: EIA-530, V.35, V.24, or X.21. The logic type signals may be any one of the following types: TTL type signals, CMOS type signals, ECL type signals or BiCMOS type signals.

In general, in another aspect, the invention is a communications interface adapter for interconnecting supporting equipment having a communications port with external equipment employing an industry standard signaling interface. The interface adapter includes a housing; a connector adapted to be plugged into the communications port, the connector providing signal paths between the outside and the inside of the housing; and an interface circuit located within the housing and connected to the first connector, the interface circuit adapted to convert logic type signals received from the communications port into signals conforming to the industry standard signaling interface for use by the external equipment.

Preferred embodiments include the following features. The interface circuit is adapted to convert signals received from the external equipment into logic type signals that are sent to the supporting equipment through the first connector. The interface circuit asserts an identification signal on at least one of the pins of the first connector, the identification signal identifying the industry standard signaling interface being implemented by the interface circuit and identifying whether the interface adapter is a DTE type or a DCE type. At least one of the pins within the first connector are dedicated to solely receiving power from the supporting equipment for the interface circuit. In general, in yet another aspect, the invention is a communications interface adapter for interconnecting supporting equipment having a communications port with external equipment employing a first communications interface. The interface adapter includes a multi-pin connector adapted to be plugged into the communications port; and an interface circuit connected to the connector, the interface circuit adapted to convert signals received from the communications port into signals conforming to the communications signaling interface for use by the external equipment, and wherein the interface circuit asserts an identification signal on at least one of the pins of the connector, the identification signal identifying the communications signaling interface being implemented by the interface circuit.

Preferred embodiments include the following features. The signals received from the communications port are logic type signals and the communications signaling interface is an industry standard signaling interface.

In general, in yet another aspect, the invention is a data communications interface for use with an interface adapter that implements an industry standard signaling interface. The data communications interface includes a communications port adapted to receive the interface adapter; and a communications module adapted to send and receive data and control signals through the communications port, the data and control signals being logic type signals; and a control module adapted to receive an identification signal through the communications port, the identification signal indicating the type of industry standard interface being implemented by said adapter cable, the control module causing said communications module to generate said logic type data and control signals in conformity with the industry standard interface.

In preferred embodiments, the identification signal includes an identification code for identifying whether the interface adapter is a DTE type or a DCE type and the control module controls said communications module in accordance with the identification code. Also, the communications module provides power for the interface adapter through a group of pins within the communications port, the group of pins dedicated solely to carrying power. An advantage of the invention is that it separates the functionality of all of the standardized communications interfaces from the electrical and physical implementation that makes each standard unique. Moreover, the burden of supplying the unique electrical and physical implementation of each standard interface is moved from within the product (e.g. the DTE or the DCE) to the cable which connects the communications ports of the products together.

Another advantage is reduced inventory requirements for the manufacture of data communications equipment. Rather than having to design, build and inventory separate interface boards for each type of data communications equipment being manufactured by the company, much of the support for each standard interface can be moved to the company level that supports the cable.

In addition, the invention does not require a separate connection through another connector to an independent power source for supplying power to perform the electrical conversions within the cable.

Furthermore, data communications equipment can be manufactured with a single communications port that employs a TTL-type interface since the invention performs the required electrical and physical conversions outside of the communications equipment.

Also, the number of communications interfaces being supported can easily and readily be expanded by adding another cable capable of performing the electrical and physical conversions required by the additional interface. Other advantages and features will become apparent from the following description of the preferred embodiment and from the claims.

Description of the Preferred Embodiment

Fig. 1 is a block diagram of a data communications system that employs an interface adapter cable;

Fig. 2 is a block diagram of an EIA-530/DCE adapter cable; Fig. 3 is a chart of the identification codes and interface types; Fig. 4 is a block diagram of a V.35 compatible DCE adapter cable;

Fig. 5 is a schematic of the balanced loads shown in Fig. 4; Fig. 6 is a block diagram of a V.24/DCE adapter cable;

Fig. 7 is a schematic of the low pass filters shown in Fig. 6;

Fig. 8 is a block diagram of an X.21/DCE adapter cable; Fig. 9 illustrates the filtering of the power lines in the interface adapter cables;

Fig. 10 is an exploded view of the interface adapter cable; and

Fig. 11 depicts the interface adapter cable and a connector mounted on a metal rear panel.

Structure and o era ion

As shown in Fig. 1, an interface adapter cable 2 provides a communications link between supporting equipment 4 and external equipment 6. Adapter cable 2 includes a 25- pin connector 8 on one end for connecting adapter cable 2 to a communications port 10 on supporting equipment 4 and it includes a different multi-pin connector 12 on its other end for connecting adapter cable 2 to a different communications port 14 on external equipment 6. Adapter cable 2 also includes an interface circuit 16 that is electrically coupled to connector 8 by data control lines 18, power lines 20 and identification code lines 22 and 24, and to connector 12 by data and control lines 26. Data and control lines 18 carry data and control signals, power lines 20 carry power for interface circuit 16 and I.D. signal lines 22 and 24 carry the identification code for indicating to supporting equipment 4 the signal requirements for adapter cable 2. In supporting equipment 4, a communications module 28 transmits and receives data and control signals through communications port 10 as standard TTL type signals. That is, supporting equipment 4 employs what shall generally be referred to as a digital interface. Other possible digital interfaces might utilize CMOS type signals, ECL type signals or BiCMOS type signals, for example. In contrast, external equipment 6 employs an industry standard data signalling interface for communications through its communications port 14. Such industry standard data signalling interfaces include, among others, EIA-530, V.35, V.24, X.21, V.36, and RS449. Adapter cable 2 implements both the electrical and the physical signal conversions required for supporting equipment 4 and external equipment 6 to communicate with each other. In one direction, interface circuit 16 converts the standard TTL type signals from communication port 10 of supporting equipment 4 to signals which conform to the standard data interface of external equipment 6. In the other direction, it converts the standard data interface signals from communication port 14 of external equipment 6 to standard TTL type signals for supporting equipment 4. Adapter cable 2 also maps the signals from the pins of connector 10 onto the appropriate corresponding pins of connector 14 so that the converted signals are sent to the proper locations in the communications ports. For each of the possible data interfaces available for external equipment 6, there is a unique interface adapter cable type to implement the required electrical and physical signal conversions.

Interface circuit 16 asserts an identification code on lines 22 and 24 that informs supporting equipment 4 about the particular data interface being implemented by adapter cable 2. Within supporting equipment 4, a control module 30 decodes the identification code and causes communications module 28 to generate its data and control signals in accordance with the requirements of the particular data interface being implemented. For example, some data interfaces, such as the EIA-530 data interface, for example, use data lines to send data signals and use separate control lines for each type of control signal. In contrast, other data interfaces, such as the X.21 data interface, for example, embed the control signals in the signals sent over the data lines and then use a single control line to carry a signal indicating how to interpret the embedded control signals. Thus, among other things, the identification code causes the communications module 28 to select the appropriate way to handle to control signals. External equipment 6 may be either a DTE (Data Terminal Equipment) or a DCE (Data Circuit-terminating

Equipment) . Supporting equipment 4, on the other hand, has "no sex" but adapter cable 2 defines whether it serves as eit.her a DTE or a DCE. As part of the identification code, interface circuit 16 indicates to supporting equipment 4 whether adapter cable 2 is a DCE or a DTE cable.

An EIA-530/DCE Interface Adapter Cable

Fig. 2 is a functional block diagram of an EIA-530 adapter cable 40 for interconnecting supporting equipment that employs a digital interface (e.g. TTL type signals) to a DTE (i.e., external equipment) that employs an EIA-530 data interface. Adapter cable 40 includes a 25-ρin digital interface (DI) connector 41, a 25-pin DTE connector 43, and an interface circuit 45. The functional block diagram shows the pin numbers for each of DI and DTE connectors 41 and 43, the circuit components used to implement the signal conversions, the assignments of pin numbers to the various circuit components and the signal functions associated with the various signal paths through cable 45. Fig. 2 also indicates the lead type (i.e., either A or B) for each of the pins on the DTE side of the cable.

Interface circuit 45 includes four balanced receivers 42(1-4), two unbalanced receivers 44(1-2), six balanced drivers 46(1-6) and one unbalanced driver 48. The following commercially available chips are used to implement these components. Two 26LS31 (Texas Instruments) balanced driver chips from AMD, each of which has four individual drivers, implement the six balanced drivers 46(1-6) (i.e., two drivers on the chips are not used) . The input signals for balanced drivers 46(1-6) are TTL type signals and the corresponding balanced drive output signals meet the requirements of recommendation EIA-422.

One UA9636 (Texas Instruments) chip containing two drivers implements unbalanced driver 48 (i.e., one driver on the chip is not used) . The input signal for driver 48 is a TTL type signal and the corresponding unbalanced drive output signal meets the requirements of recommendation EIA- 423.

One 26LS32 chip containing four receivers implements the four balanced receivers 42(1-4). The input signals for receivers 42(1-4) meet the requirements of recommendation EIA-422 and the corresponding output signals are TTL type signals.

Finally, a second 26LS32 chip implements the two unbalanced receivers 44(1-2). Non-inverting inputs of the receivers on this chip are tied to ground. The input signals meet the requirements of recommendation EIA-423 and the corresponding output signals are TTL type signals.

Pins 24, 14, and 18 of DI connector 41 supply three components of the identification code, namely, IDO, IDl and ID2, respectively, to the supporting equipment. Each of these components of the identification code may be either high or low. Pin 19 of DTE connector 41 supplies a fourth component of the identification code, namely, DTE/ DCE , which indicates whether adapter cable 40 is for a DTE or DCE, depending on whether it is high or low, respectively. Interface circuit 45 includes an ID code signal generator 47 and a DTE/ DCE code generator 49 for generating the identification code that is appropriate for the adapter cable. In this embodiment (i.e., a cable which converts TTL type level signals to EIA-423 signals for a DTE), IDO, ID1, and ID2 are high, low, low, respectively, and DTE/ DCE is low.

Identification codes for other adapter cable types are shown in Fig. 3. For purposes of indicating the data interface type being implemented by the adapter cable,

DTE/ DCE is irrelevant and thus "X's" appear in the chart in Fig. 3 under the column heading DTE/ DCE . Also note that highs on all pins 14, 18, 19, and 24 of DI connector 41 signifies that no adapter cable is attached to the supporting equipment. Within control module 30 of supporting equipment 4, the lines which correspond to pins 14, 18, 19, and 24 of DI connector 41 are connected to a high voltage level through a 4.7K ohm resistor (not shown in the figures) so that if no adapter cable is connected to the supporting equipment, the signals on those lines are pulled high, thereby informing control module 30 that no cable is attached.

Interface circuit 45 obtains power for its internal circuitry through pins 20, 21, 22, and 23 of DI interface connector 41 which connect to +5 volt, +12 volt, -12 volt, and ground levels, respectively, within supporting equipment 4 when coupled to the communication port of the supporting equipment.

A V.35 Compatible DCE Interface Adapter Cable

Fig. 4 is a functional block diagram of a V.35 compatible adapter cable 50 for interconnecting supporting equipment that employs a digital interface (e.g. TTL type signals) to a DTE that employs a V.35 compatible data interface. Adapter cable 50 includes a 25-pin DI connector 51, a 25-pin DTE connector 53, and an interface circuit 55. The functional block diagram shows the pin numbers for each of DI and DTE connectors 51 and 53, the circuit components used to implement the signal conversions, the assignments of pin numbers to the various circuit components and the signal functions associated with the various signal paths through cable 55. Fig. 4 also indicates the lead type (i.e., either A or B) for each of the pins on the DTE side of the cable.

Adapter cable 50 includes two balanced receivers 52(1- 2) , each of which has a balanced receiver load 60 on its input, two unbalanced receivers 54(1-2), three balanced drivers 56(1-3) and four unbalanced drivers 58(1-4) . The following commercially available chips are used to implement these components.

To limit heat dissipation within adapter cable 50, balanced drivers meeting recommendation V.ll are used in place of the balanced driver described in recommendation V.35 Appendix II. The V.ll-type driver generates less heat than the V.35 type balanced driver. None of the electrical characteristics for the load described in recommendation V.35 Appendix II limit the balanced receivers of a V.35 interface from working with a V.ll type drivers and it is assumed that most V.35 interfaces use V.ll compatible receivers. Balanced receivers within the V.35 interface adapter cable 50 will also be V.ll compatible and meet the load requirements of V.35.

One 26LS32 chip implements the two balanced receivers 52(1-2) . The input signals to both balanced receivers 52(1-2) meet the requirements of recommendation V.ll and are supplied via balanced receiver loads 60. The corresponding output signals of balanced receivers 52(1-2) are TTL type signals.

Balanced loads 60(1-2) are shown in Fig. 5. The inputs to the load are protected from shorts to other interchange circuits within the V.35 interface by 1N4004 type diodes.

Two MC145406 (Motorola) chips containing three receivers and three transmitters each implement unbalanced receivers 54 (1-2) . Only two of the six available receivers are used for the V.35 compatible interface. The input signals for unbalanced receivers 54(1-2) meet the requirements of recommendation V.28 and the corresponding output signals are TTL type signals. One 26LS31 balanced driver chip implements the three balanced drivers 56(1-3) . The input signals for the balanced drivers 56(1-3) are TTL type signals and the corresponding balanced drive output signals meet the requirements of recommendation V.ll.

Finally, the two MC1 5406 chips also implement the four unbalanced drivers 58(1-4) . The input signals for the unbalanced drivers are TTL type signals and the corresponding output signals meet the requirements of recommendation V.28.

Pins 19, 24, 14, and 18 of DI connector 51 supply DTE/ DCE , IDO, IDl and ID2, respectively, to the supporting equipment . Interface circuit 55 includes an ID code signal generator 57 and a DTE/ DCE code generator 59 for generating the identification code that is appropriate for this adapter cable. In this embodiment, IDO, IDl, and ID2 are low, high, low, respectively, and DTE/ DCE is low.

Interface circuit 55 obtains power for its internal circuitry through pins 20, 21, 22, and 23 of DI interface connector 51 which connect to +5 volt, +12 volt, -12 volt, and ground levels, respectively, within the supporting equipment when coupled to the communication port of the supporting equipment.

An RS232/V.24 DCE Interface Adapter Cable

Fig. 6 is a functional block diagram of an RS232/V.24 adapter cable 70 for interconnecting supporting equipment that employs a digital interface (e.g. TTL type signals) to a DTE that employs a V.24 data interface. Adapter cable 70 includes a 25-pin DI connector 71, a 25-pin DTE connector 73, and an interface circuit 75. The functional block diagram shows the pin numbers for each of DI and DTE connectors 71 and 73, the circuit components used to implement the signal conversions, the assignments of pin numbers to the various circuit components and the signal functions associated with the various signal paths through cable 75. Interface adapter cable 70 includes six receivers 74(1-6), each of which is preceded by a low-pass filter 76, and eight drivers (72(1-8) . The following commercially available chips are used to implement these components. Three MC145406 chips implement the eight drivers 72(1- 8) . The input signals for drivers 72(1-8) are TTL type signals and the corresponding output signals meet the requirements of recommendation V.24.

The three MC145406 chips also implement the six receivers 74(1-6) . The input signals for receivers 74(1-6) meet the requirements of recommendation V.24 and the corresponding output signals are TTL type signals .

Low-pass filter 76 is shown in Fig. 7. Each low-pass filter 76 is used to reduce line ringing. Pins 19, 24, 14, and 18 of DI connector 71 supply

DTE/ DCE , IDO, IDl and ID2, respectively, to the supporting equipment. Interface circuit 75 includes an ID code signal generator 77 and a DTE/ DCE code generator 79 for generating the identification code that is appropriate for this adapter cable. In this embodiment, IDO, IDl, and ID2 are low, low, high, respectively, and DTE/ DCE is low.

Interface circuit 75 obtains power for its internal circuitry through pins 20, 21, 22, and 23 of DI connector 71 which connect to +5 volt, +12 volt, -12 volt, and ground levels, respectively, within the supporting equipment when coupled to the communication port of the supporting equipment.

An X.21 DCE Interface Adapter Cable Fig. 8 is a functional block diagram of an X.21 adapter cable 80 for interconnecting supporting equipment that employs a digital interface (e.g. TTL type level signals) to a DTE that employs an X.21 data interface. Adapter cable 80 includes a 25-pin DI connector 81, a 15- pin DTE connector 83, and an interface circuit 85. The functional block diagram shows the pin numbers for each of DI and DTE connectors 81 and 83, the circuit components used to implement the signal conversions, the assignments of pin numbers to the various circuit components and the signal functions associated with the various signal paths through cable 85. Fig. 8 also indicates the lead type (i.e., either A or B) for each of the pins on the DTE side of the cable.

Interface adapter cable 80 includes three balanced drivers 82(1-3) and two receivers 84(1-2). The following commercially available chips are used to implement these components.

One 26LS31 balanced driver chip implements the three drivers 82(1-3). The input signals for balanced drivers 82(1-3) are TTL type signals and the corresponding output balanced drive signals meet the requirements of recommendation X.21.

One 26LS32 balanced receiver chip implements the two receivers 84(1-2). The input signals for receivers 84(1-2) meet the requirements of recommendation X.21 and the corresponding output signals are TTL type signals. Note that the output of receiver 84(2) is sent to both pin 1 and pin 3 of DTE connector 81.

Pins 19, 24, 14, and 18 of DI connector 81 supply DTE/ DCE , IDO, IDl and ID2, respectively, to the supporting ' equipment. Interface circuit 85 includes an ID code signal generator 87 and a DTE/ DCE code generator 89 for generating the identification code that is appropriate for this adapter cable. In this embodiment, IDO, IDl, and ID2 are low, high, high, respectively, and DTE/ DCE is low.

Interface circuit 85 obtains power for its internal circuitry through pins 20 and 23 of DI connector 81 which connect to +5 volt and ground levels, respectively, within the supporting equipment when coupled to the communication port of the supporting equipment. Pins 21 and 22, as in the other cables described above, receive +12 volts and -12 volts, respectively, from the supporting equipment.

However, the voltages at pins 21 and 22 are not used within interface adapter cable 80. For the EIA-530, the V.35 compatible and the V.24 adapter cables described above, filtering of the supply voltages provided to the interface circuit through the DI connector is done as shown in Fig. 9. The interface circuit includes a +12 volt supply line 102, a +5 volt supply line 104, a -12 volt supply line 106, and a ground line 108. Each of supply lines 102, 104, and 106 is connected to its corresponding pin 21, 20, and 22, respectively, of the digital connector through a corresponding one of three ferrite bead inductors 110. In addition, each of supply lines 102, 104 and 106 is connected to ground line 108 through a corresponding one of three 0.1 μf capacitors 112. In the X.21 adapter interface cable, the +5 volt supply line is filtered as shown in Fig. 9, and the voltages at pins 21 and 22 are not utilized.

Interface circuit 16 and 25-pin connector 8 (in Fig. 1) are part of a single assembly 200, as shown in Fig. 10. Assembly 200 includes a die cast aluminum base plate 202 which provides a heat conducting path for dissipating heat generated by interface circuit 16, a printed wire assembly (PWA) 204 which contains interface circuit 16, a thin adhesive pad 206 for affixing PWA 204 to base plate 202, and a plastic cover 208 which snaps onto base plate 202.

Interface circuit 16 is fabricated on PWA 204 by using standard surface mount technology. Connector 8 is affixed to one end of PWA 204 and is electrically connected to interface circuit 16. A second connector 210 is mounted at the opposite end of PWA and is also electrically connected to interface circuit 16. A shielded cable 212 containing data and control lines 26 shown in Fig. 1 is connected to interface circuit 16 through connector 210. One end of shielded cable 212 includes a stress relief grommet 214 and the other end of shielded cable 212 includes connector 12 for connecting to the communications port of the external equipment (not shown in Fig. 10) .

Base plate 202 includes a structure 218 at its back end and, as shown in greater detail in the enlarged view, a foot 216 at its front end. Structure 218 receives grommet 214 and provides an anchor for cable 212. Foot 216 is a raised portion along the edge of base plate 202 that has a flat surface 220 which is approximately 1/8 inch high by 2.29 inches wide. Foot 216 serves as an alignment guide for affixing PWA 204 onto base plate 202 during assembly and it provides a thermal contact area for transferring heat into a metal rear panel 222 of the supporting equipment (see Fig. 11) when assembly 200 is attached to the supporting equipment. Along its sides, base plate 202 also includes rails 224 to which cover 208 attaches when it is snapped onto base plate 202.

Cover 208 includes an alignment key 228 which slides into a corresponding slot 230 above connector 10 on rear panel 222 when assembly 200 is connected to the supporting equipment. Once connected, assembly 200 is secured in place by screwing two thumbscrews 226 into corresponding threaded holes 232 in rear panel 222. Thumbscrews 226 assure that foot 216 makes good thermal contact with rear panel 222 in a thermal contact area 234 shown in Fig. 11 as a shaded region below connector 10.

Since the thermal conductivity of adhesive pad 206 is roughly proportional to its thickness, the total thermal load associated with interface circuit 16 and the desired limit on temperature rise of assembly 200 during operation provides a guide to how thin adhesive 206 must be. In the described embodiment, adhesive pad 206 is an 0.005 inch thick acrylic pressure-sensitive adhesive material cut from a roll of A-10 adhesive manufactured by 3M (product number 9469PC) that has a release liner on one side. Adhesive pad 206 is applied to base plate 202 with the release liner intact. When it is time to affix PWA 204 onto base plate 202, the release liner is removed and PWA 204 laid in place with a minimum of hand pressure. Other embodiments are within the following claims.

What is claimed is:

Claims

Claims 1. A communications interface adapter for interconnecting supporting equipment having a first communications port with external equipment having a second communications port, the external equipment communicating through the second communications port in accordance with an industry standard signaling interface, the interface adapter comprising: a first multi-pin connector adapted to plug into the first communications port; an interface circuit connected to the first connector, the interface circuit being adapted to convert logic type signals received from the communications port into signals conforming to the industry standard signaling interface; a second multi-pin connector adapted to plug into the second communications port; and a cable connecting the interface circuit to the second connector for carrying the converted signals to the external equipment.

2. The interface adapter of claim 1 wherein the interface circuit is adapted to convert signals received from the external equipment into logic type signals that are sent to the supporting equipment through the first connector.

3. The interface adapter of claims 1 or 2 wherein the interface circuit asserts an identification signal on at least one of the pins of the first connector, said identification signal identifying the industry standard signaling interface being implemented by the interface circuit.

4. The interface adapter of claim 2 wherein said identification signal also identifies whether the interface adapter is a DTE type or a DCE type.

5. The interface adapter of claims 1 or 2 wherein at least one of the pins within said first connector are dedicated to solely receiving power from the supporting equipment for the interface circuit.

6. The interface adapter of claim 3 wherein the industry standard signaling interface is EIA-530.

7. The interface adapter of claim 3 wherein the industry standard signaling interface is V.35.

8. The interface adapter of claim 3 wherein the industry standard signaling interface is V.24.

9. The interface adapter of claim 3 wherein the industry standard signaling interface is X.21.

10. The interface adapter of claim 3 wherein the logic type signals are TTL type signals.

11. The interface adapter of claim 3 wherein the logic type signals are CMOS type signals.

12. The interface adapter of claim 3 wherein the logic type signals are ECL type signals.

13. The interface adapter of claim 3 wherein the logic type signals are BiCMOS type signals.

14. A communications interface adapter for interconnecting supporting equipment having a communications port with external equipment employing an industry standard signaling interface, the interface adapter comprising: a housing; a connector adapted to be plugged into the communications port, said connector providing signal paths between the outside and the inside of said housing; and an interface circuit located within said housing and connected to the first connector, the interface circuit adapted to convert logic type signals received from the communications port into signals conforming to the industry standard signaling interface for use by the external equipment.

15. The interface adapter of claim 14 wherein the interface circuit is adapted to convert signals received from the external equipment into logic type signals that are sent to the supporting equipment through the first connector.

16. The interface adapter of claims 14 or 15 wherein the interface circuit asserts an identification signal on at least one of the pins of the first connector, said identification signal identifying the industry standard signaling interface being implemented by the interface circuit.

17. The interface adapter of claim 14 wherein said identification signal also identifies whether the interface adapter is a DTE type or a DCE type.

18. The interface adapter of claims 14 or 15 wherein at least one of the pins within said first connector are dedicated to solely receiving power from the supporting equipment for the interface circuit.

19. A communications interface adapter for interconnecting supporting equipment having a communications port with external equipment employing a first communications interface, the interface adapter comprising: a multi-pin connector adapted to be plugged into the communications port; and an interface circuit connected to the connector, the interface circuit adapted to convert signals received from the communications port into signals conforming to the communications signaling interface for use by the external equipment, and wherein the interface circuit asserts an identification signal on at least one of the pins of the connector, said identification signal identifying the communications signaling interface being implemented by the interface circuit.

20. The interface adapter of claim 19 wherein the signals received from the communications port are logic type signals.

21. The interface adapter of claim 19 wherein the communications signaling interface is an industry standard signaling interface.

22. The interface adapter of claims 14, 15 or 19 wherein the logic type signals are TTL type signals.

23. The interface adapter of claims 14, 15 of 19 wherein the logic type signals are CMOS type signals.

24. The interface adapter of claims 14, 15 or 19 wherein the logic type signals are ECL type signals.

25. The interface adapter of claims 14, 15 or 19 wherein the logic type signals are BiCMOS type signals.

26. The interface adapter of claims 14 or 21 wherein the industry standard signaling interface is EIA-530.

27. The interface adapter of claims 14 or 21 wherein the industry standard signaling interface is V.35.

28. The interface adapter of claims 14 or 21 wherein the industry standard signaling interface is V.24.

.

29. The interface adapter of claims 14 or 21 wherein the industry standard signaling interface is X.21.

30. The interface adapter of claims 19 wherein said identification signal also identifies whether the interface adapter is a DTE type or a DCE type.

31. The interface adapter of claim 19 wherein at least one of the pins within said multi-pin connector are dedicated to solely receiving power from the supporting equipment for the interface circuit.

32. A data communications interface for use with an interface adapter that implements an industry standard signaling interface, the data communications interface comprising: a communications port adapted to receive the interface adapter; a communications module adapted to send and receive data and control signals through said communications port, said data and control signals being logic type signals; and a control module adapted to receive an identification signal through said communications port, said identification signal indicating the type of industry standard interface being implemented by said adapter, said control module causing said communications module to generate said logic type data and control signals in conformity with said industry standard interface.

33. The data communications interface of claim 32 wherein the industry standard signaling interface is EIA- 530.

34. The data communications interface of claim 32 wherein the industry standard signaling interface is V.35.

35. The data communications interface of claim 32 wherein the industry standard signaling interface is V.24.

36. The data communications interface of claim 32 wherein the industry standard signaling interface is X.21.

37. The data communications interface of claim 32 wherein said identification signal comprises an identification code for identifying whether the interface adapter is a DTE type or a DCE type and wherein said control module controls said communications module in accordance with said identification code.

38. The data communications interface of claim 32 wherein said communications module provides power for the interface adapter through a group of pins within said communications port, said group of pins dedicated solely to carrying power.

39. The data communications interface of claim 32 wherein the logic type signals are TTL type signals.

40. The data communications interface of claim 32 wherein the logic type signals are CMOS type signals.

41. The data communications interface of claim 32 wherein the logic type signals are ECL type signals.

42. The data communications interface of claim 32 wherein the logic type signals are BiCMOS type signals.