IES69756B2 - A diverter device for a computer and a computer containing the diverter device - Google Patents

Abstract

A diverter (12, 14, 15) for locating in a computer (1) for communicating applications software (8) with one of a modem port (2) and a CAPI compliant ISDN port (6) for communicating the computer (1) with another computer on a PSTN (5) or an ISDN (7). The diverter (12, 14, 15) is transparent to the applications software (8) and is located between the applications software (8) and a COMM driver (10), and an identifying and diverting part (14) of the diverter (12) sits on top of the COMM driver (10). The identifying and diverting part (14) determines whether communication is to be through the modem port (2) or the ISDN port (6), and diverts commands and data from the applications software (8) to the appropriate port (2, 6). Commands and data for the modem port (2) are passed directly through the identifying and diverting part (14) to the COMM driver (10). Commands and data for the ISDN port (6) are diverted by the identifying and diverting part (14) through the ISDN driver (15) to the ISDN port (6).

Description

A diverter device for a computer, and a computer containing the diverter device The present invention relates to a diverter device for use in a computer having applications software resident therein, whereby the applications software is suitable for running over a modem for communicating with another computer over a public switched telephone network (PSTN), the diverter device being suitable for allowing the applications software to communicate with another computer over an integrated services digital network (ISDN). The invention also relates to a computer comprising the diverter device, and to a method for operating a computer for allowing applications software resident therein to communicate with another computer over an ISDN.

Where applications software for communicating a computer on a PSTN is resident in a computer, the applications software is in general only suitable for communicating through a modem. Attempts have been made to provide such applications software with a facility for communicating with other computers through an ISDN, however, to date, while such attempts have met with limited success, in general, it is not possible to run applications software which is designed for operating over a modem on an ISDN and achieve transfer of data at SM75< ’ the relatively rapid rate at which ISDN facilitate. In « general, in order to enable such applications software to communicate on an ISDN, it is necessary to provide « additional software in the computer. Such additional software, in general, is provided in the computer at the same level as the applications software, and thus, cannot operate simultaneously with the applications software. In Windows 3.1 operating systems applications software runs non-preemptively, therefore, one applications software must yield control to allow a second applications software to run. In the case of COMM software, where the applications do not yield control until data has been sent out through the modem, the applications software must wait to perform correctly when the system requires two applications software to run simultaneously.

There is therefore a need for a method and a device for use in a computer which enables applications software designed for use with a modem on a PSTN to be used on an ISDN, while at the same time enabling full advantage to be taken of the high speed data transfer facilitated by ISDN. There is also a need for a computer comprising such a device and operating under such a 4 method.

The present invention is directed towards providing such a device, a method and a computer.

According to the invention there is provided a computer comprising a modem port for connecting to a modem for communicating with a PSTN, applications software resident in the computer for communicating the computer through the modem port for permitting communication with the PSTN through the modem, a comm driver for communicating the applications software with the modem port, wherein a diverter device is provided in the computer between the applications software and the comm driver, the diverter device being transparent to the applications software and allowing commands and data to pass therethrough uninterrupted to the comm driver where data is to be sent by the applications software through the modem, and for diverting commands and data to be sent to a port configured for connecting to an ISDN, the diverter device also comprising an interface means for interfacing with the ISDN, and for sending data over the ISDN, and a conversion means for converting commands in modem format to the equivalent commands associated with ISDN, the diverter device being operable in the computer simultaneously with the applications software for communicating the applications software with the ISDN.

In one aspect of the invention the applications software comprises a means for identifying the port « through which data is to be sent, the diverter device being responsive to the applications software for *> directing commands and data to the ISDN port by the applications software identifying the ISDN port, and for allowing commands and data to pass therethrough directly to the comm driver on the applications software identifying the modem port.

In another aspect of the invention the diverter device 10 is responsive to an OPENCOMM command from the applications software, the OPENCOMM command being a Windows 3.1 systems applications programming interface command, and the diverter device comprises a means for reading the OPENCOMM command for determining the identity of the port through which the commands and the data are to be sent.

In another aspect of the invention the diverter device is responsive to a CLOSECOMM command from the applications software for returning the diverter device to a waiting mode for awaiting the next OPENCOMM command.

Preferably, the ISDN interface means comprises an ISDN driver, and preferable, the ISDN driver initialises memory locations and sets up a line in the ISDN network on receiving an ATD command from the applications software through the diverter device. In one aspect of the invention the ISDN driver sets up a line on one Bchannel on the line of the ISDN, and in another aspect of the invention the ISDN driver sets up two B-channels on the line of the ISDN.

In a further aspect of the invention the diverter device sends the data in packets over the line of the ISDN, and in one embodiment of the invention where two B-channels are established on the ISDN line, the data packets are sequentially numbered, substantially one half of all the data packets being sent on one Bchannel and substantially the other half of all the data packets being sent on the other B-channel.

In a further aspect of the invention the diverter device calls up an appropriate sub-routine in ISDN format in response to a corresponding command in modem format received from the applications software, for communicating the applications software with the ISDN.

In a further embodiment of the invention the diverter device is implemented in software, and sits just above the comm driver.

Additionally, the invention provides the diverter device for operating in a computer, and preferably, the diverter device is implemented in software.

Further, the invention provides a method for operating a computer under the control of applications software and the diverter device for communicating the applications software with an ISDN, the applications software and the diverter device being operable simultaneously in the computer.

The invention will be more clearly understood from the 10 following description of an embodiment thereof which is given by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a block representation of a computer according to the invention comprising a diverter device also according to the invention located therein, Fig. 2 is a block representation of a flowchart illustrating the operation of the diverter device of Fig. 1, and Fig. 3 is a block representation of a flowchart which also illustrates the operation of the diverter device of Fig. 1.

Referring to the drawings there is illustrated a computer according to the invention indicated generally by the reference numeral 1 which comprises applications software 2 for communicating with another computer over a PSTN 3 through a modem 4 which is separate from the computer 1. The modem 4 is connected to the computer 1 through a modem port 5. A comm driver 6 which is implemented in software is located in the computer between the applications software 2 and the modem port 5 for communicating the applications software 2 through the modem port 5 with the modem 4. Located between the applications software 2 and the comm driver 6 is a diverter device 8 also according to the invention which sits on top of the comm driver 6 for facilitating communication of the applications software 2 through a separate port 10 of the computer 1 which is configured for communicating with an ISDN 9. The applications software 2 is suitable for communicating over the modem 5 and accordingly, outputs commands in modem format.

The diverter device 8 is implemented in software and is transparent to the applications software 2 and the comm driver 6, so that in the event that the applications software 2 is to communicate through the modem 4 all commands and data from the applications software 2 pass through the diverter device 8 and onto the comm driver 6. Additionally, as will be described below the diverter device 8 is operable in the computer 1 simultaneously with the applications software 2 for communicating the applications software 2 with the ISDN port 10 for communication with the ISDN 9. In this way, full advantage of the speed at which data may be transmitted over the ISDN 9 may be taken, and there is no delay in communicating the applications software 2 with the ISDN 9 through the ISDN port 10.

The diverter device 8 comprises two parts, both of which are implemented in software, firstly, an identifying part 11 which is the part which sits above the comm driver 6 for identifying which of the two ports, namely, the modem port 5 and the ISDN port 10 has been selected by the applications software 2, and an interface means for interfacing with the ISDN 9, which in this case is an ISDN driver 12. The ISDN driver 12 is located adjacent the ISDN port 10.

Although needless to say, it will be appreciated that the two parts, namely, the identifying part 11 and the ISDN driver part 12 may be located together on top of the comm driver 6.

The diverter device 8 will now be described in detail with reference to the flow charts of Figs. 2 and 3.

The flowchart of Fig. 2 illustrates the operation of the identifying part 11 of the diverter device 8, while the flowchart of Fig. 3 illustrates the operation of the ISDN driver part 12 of the diverter device 8. In this embodiment of the invention the applications software 2 as discussed above issues commands and sends data in modem format. When the applications software 2 wishes to communicate over a PSTN or an ISDN the applications software 2 issues an OPENCOMM command which includes a character or characters which identify the port 5 or 10 through which the data is to be transmitted.

Referring now in particular to Fig. 2 the identifying part 11 of the diverter device 8 comprises a block 20 which starts operation of the diverter device 8. On calling up of the applications software 2 in the computer 1, block 20 is activated for activating the diverter device 8. On block 20 having been activated, the software of the diverter device 8 moves to block 21 which waits for and reads commands from the applications software 2. On block 21 having read a command, the software moves to block 22 which checks if the read command is an OPENCOMM command. If not, the software returns to block 21. Should block 22 determine that the command read in block 21 is an OPENCOMM command, the software moves to block 25 which checks if the character included in the OPENCOMM command has identified the modem port 5. If so, the software moves to block 26 which allows communication directly through the diverter device 8 between the applications software 2 and the modem port 5. The software then moves between block 26 and a block 27 which checks for a CLOSECOMM command from the applications software. On block 27 determining that a CLOSECOMM command has been read by the identifying part 11 of the software, the software returns to block 21.

Should block 25 determine that the characteristic included in the OPENCOMM command does not identify the modem port 5 the software moves to block 30 which checks if the character in the OPENCOMM command has identified the ISDN port 10. If not, the software returns to block 21. Should block 30 determine that the character included in the OPENCOMM command has identified the ISDN port 10, the software moves to block 33. Block 33 calls up the ISDN driver part 12 of the diverter device 8. The operation of the ISDN driver software will be described below with reference to Fig. 3. The software then moves to block 34 which waits for an identifier from the ISDN driver software, and then moves to block 35. Block 35 reads the identifier and stores it and writes the identifier to the applications software 2, so that all subsequent commands and data to be sent to the ISDN port 10 will contain the identifier. Typically, the identifier is a single digit number. The software moves to block 38 which allows direct communication between the applications software 2 and the ISDN driver 12 through the identifying part 11 of the diverter device 8. The applications software sends data to the ISDN driver 12 via a WRITE COMM command. The identifying part 11 of the diverter device 8 then cycles between block 38 and the block 39 which checks if a CLOSECOMM signal has been sent by the applications software 2. On block 39 determining that a CLOSECOMM signal has been sent by the applications software 2 the software is returned to block 21.

Referring now to Fig. 3 the operation of the ISDN driver 12 will now be described. Block 50 of the ISDN driver 12 starts the driver software in response to block 33 of the identifying part 11 of the software.

On being activated the ISDN driver software moves to block 51 which initialises memory locations in the ISDN driver 12 and moves to block 52 which generates and writes the identifier to the software of the identifying part 11 of the diverter device 8 which is read by block 35 for subsequent writing to the applications software 2 as already described.

On writing the identifier to the identifying part 11 of the diverter device 8 the ISDN driver software moves to block 54 which waits for a command or a data stream from block 38 of the identifying part 11. The ISDN driver software then moves to block 55 which reads the command or data stream received from block 38 of the identifying part 11. The ISDN driver 12 then moves to block 56 which checks if the command or data stream is accompanied by the identifying. If not, the software is returned to block 54. On block 56 determining that the command or data stream comprises the identifying, the software moves to block 57 which checks if it was a command that was read by block 55. If not, the software moves to block 58 which checks if it was a data stream that was read by block 55, and if not, the software returns to block 54. On block 58 determining that it was a data stream that was read by block 55 the software moves to block 60 which will be described below.

On block 57 determining that a command was read by block 55, the software moves to block 62. Block 62 checks if the command received from the applications software 2 was a modem command ATD instructing that a line of the ISDN be established. If so, the software moves to block 63 which calls up a standard dial subroutine for dialling an ISDN line and establishing one of the channels of the ISDN line. The software then moves to block 64 which waits for confirmation from the sub-routine of block 63 that a line has been established. The software then moves to block 65 which checks if a line has been established, and if not, the software is returned to block 63. On block 65 determining that a line has been established the software moves to block 66 which, if a second B-channel of the ISDN line is to be established, checks if the second B-channel has been established. In this embodiment of the invention, since an ISDN line comprises two B-channels, in order to avail of the two B-channels for speeding up the transfer of data from the computer to another computer over the ISDN, a facility is provided for enabling the user to select either one or two B-channels. If a second B-channel is to be established, and block 66 determines that the second B-channel has not been established, the software returns to block 63. On block 66 determining that the second B-channel has been established, the software moves to block 68 which confirms that a line has been established to block 36 of the identifying part 11 of the diverter device 8, and the ISDN driver software is returned to block 54. Should the ISDN driver software be instructed to establish two B-channels, on the two B-channels having been established, the software also moves to block 68 which returns the software to block 54. The operation of the software from block 54 after the B-channels or channels, as the case may be, have been established will be described below. However, before describing this part of the ISDN driver software 9' in detail, the remainder of the software from block 62 will now be described. r Should block 62 determine that the command from the applications software 2 is not an ATD modem command, the software moves to block 70. Block 70 checks if the command from the applications software 2 is an ATH modem command, namely, a command that the ISDN telephone line is to be terminated, and if block 70 determines that the command is an ATH command the software moves to block 71 which calls up a standard hang-up sub-routine terminating the ISDN line. Should block 70 determine that the command is not an ATH command, the software moves to block 72 which checks if the command is an ATZ modem command, namely, a reset command. If so, the software moves to block 73 which resets the driver software. Should block 72 determine that the command is not an ATZ command the software moves to block 74 which checks if the command is an ATS0=l modem command. If so, the software moves to block 75 which instructs the ISDN driver software to answer any subsequent incoming ISDN calls through the ISDN port 10 which are directed by the ISDN driver 12 < through the identifying part 11 to the applications software 2 as will briefly be described below. Should block 74 determine that the command is not an ATS0-1 command, the ISDN driver software moves to block 76 which returns the ISDN driver software to block 50 and returns control to the identifying part 11 of the diverter driver 8 at block 21.

Returning now to the operation of the ISDN driver software after block 68 returns the software to block 54, once the ISDN line has been established the applications software 2 sends a data stream using the WRITECOMM command for transmission on the ISDN network for which block 54 waits. The software then as already described moves to block 55 and on determining that a data stream has been received by block 54, block 55 reads the data, and the software moves to block 56 which checks if the identifying number accompanies the data stream. If so, which will most likely be the case, the software moves to block 57 which on determining that the data stream is not a command moves the software to block 58. On block 58 determining that a data stream has been read by block 54, the software moves to block 60. Block 60 checks the speed at which the data is to be transferred. If the data is to be transferred at 128 bits per second, two B-channels will have been established by the sub-routine of block 63.

On the other hand, if the data is not to be transferred at a speed of 128 bits per second, the data will be transferred at 64 bits per second on a single B16 channel.

On block 60 determining that the data is not to be transferred at 128 bits per second, the software moves to block 80. Block 80 forms the data into packets and moves to block 81 which sends the data in packets sequentially on the B-channel established on the ISDN. Block 81 returns the software to block 54 to await further data for transmission as already described.

Should block 60 determine that the data is to be transferred at 128 bits per second, the software moves to block 85 which forms the data into packets and sequentially numbers the packets. The software moves to block 86 which sends the data in packets sequentially on the two B-channels on the ISDN line.

The packets are sent on the B-channels in such a way that approximately half the packets are sent on one Bchannel and the other half of the packets are sent on the other B-channel. Typically, alternate packets are sent on the respective B-channels. For example, all packets with even numbers are sent one B-channel and all packets with uneven numbers are sent on the other B-channel. The sequential numbering of the data packets enables them to be reassembled in the correct order by the computer receiving the data. The software then returns to block 54 to await the next data stream.

Returning to block 75, once the ISDN port 10 has been activated to receive incoming calls on the ISDN network, a sub-routine of the ISDN driver is called up. The operation of the sub-routine for receiving calls and communicating the calls with the applications software 2 is essentially the reverse of the software of the ISDN driver 12 which has just been described with reference to Fig. 3. Incoming commands in ISDN format are converted to commands in modem format and relayed to the applications software 2 through the identifying part 11 of the diverter device 8. Such an arrangement of software will be readily apparent to those skilled in the art.

Additionally, the sub-routine of the ISDN driver 12 for answering and receiving calls comprises an algorithm for receiving data on two B-channels of an ISDN line, in other words, for receiving data at the rate of 128 bits per second which avoids slowing down of the data transmission in the event of minor corruption of the data. Briefly, the algorithm receives the numbered packets of data and arranges them sequentially. Should it be determined that a packet of data is missing, the sub-routine waits for aipredetermined period of time, which in this case, is five seconds. On the missing packet of data being received the receive sub-routine continues to assemble the data packets sequentially in numbered order. On the missing data not appearing within the five second predetermined period the receive sub-routine looks for the next data packet numbered sequentially upwards from the B-channel from which the data packet is missing. If a higher numbered packet is found, but the higher numbered packet .is not the next sequentially numbered packet, the receive sub-routine waits for a further three seconds for the missing said next sequentially numbered packet of data to appear.

If after three seconds the missing said next sequentially numbered packet has not appeared, the receive sub-routine then takes the said next higher numbered packet and the software then commences to synchronise the data packets in number order being received on the two B-channels.

The advantages of the invention are many. Firstly, by virtue of the fact that the diverter device 8 is mounted on top of the comm driver 6 and is transparent, the applications software 2 can communicate directly through the modem 4 without any delay. Furthermore, by virtue of the fact that the software of the diverter device 8 can operate simultaneously with the applications software 2 there is no delay in communicating the applications software 2 with the ISDN port 10 and in turn the ISDN network, and full advantage of the rapid rate at which data can be transferred on ISDN, either at 64 bits per second or at 128 bits per second can be fully utilised.

The invention is not limited to the embodiment hereinbefore described which may be varied in construction and detail.

Claims (5)

1. A computer comprising a modem port for connecting to a modem for communicating with a PSTN, applications software resident in the computer for communicating the 5 computer through the modem port for permitting communication with the PSTN through the modem, a COMM driver for communicating the applications software with the modem port, wherein a diverter device is provided in the computer between the applications software and 10 the COMM driver, the diverter device being transparent to the applications software and allowing commands and data to pass therethrough uninterrupted to the COMM driver where data is to be sent by the applications software through the modem, and for diverting commands 15 and data to be sent to a port configured for connecting to an ISDN, the diverter device also comprising an interface means for interfacing with the ISDN, and for sending data over the ISDN, and a conversion means for converting commands in modem format to the equivalent 20 commands associated with the ISDN, the diverter device being operable in the computer simultaneously with the applications software for communicating the applications software with the ISDN.

2. A computer as claimed in Claim 1 in which the 25 applications software comprises a means for identifying the port through which data is to be sent, the diverter device being responsive to the applications software for directing commands and data to the ISDN port by the applications software identifying the ISDN port, and for allowing commands and data to pass therethrough 5 directly to the COMM driver on the applications software identifying the modem port.

3. A computer as claimed in Claim 1 or 2 in which the diverter device calls up an appropriate sub-routine in ISDN format in response to a corresponding command in 10 modem format received from the applications software, for communicating the applications software with the ISDN.

4. A computer comprising a modem port for connecting to a modem for communicating with a PSTN, applications 15 software resident in the computer for communicating the computer through the modem port for permitting communication with the PSTN through the modem, a COMM driver for communicating the applications software with the modem port, and diverter device located in the 20 computer between the applications software and the COMM driver, the diverter device being substantially as described herein with reference to and as illustrated in the accompanying drawings.

5. A diverter device for operating in a computer as claimed in any preceding claim.