GB2267801A

GB2267801A - Connecting computers and peripheral devices

Info

Publication number: GB2267801A
Application number: GB9212078A
Authority: GB
Inventors: Leandre Edward Augusti Mcateer
Original assignee: Individual
Current assignee: Individual
Priority date: 1992-06-08
Filing date: 1992-06-08
Publication date: 1993-12-15
Also published as: GB9212078D0

Abstract

An electronic circuit which includes interpretive circuitry, permits standard computers to be networked using RS485 lines convened to RS232 for connection to their serial interface, all linked to one serial port on the main host computer. The circuit also links the 'slave' computers to machinery, which can be controlled and monitored by the computers by means of serial information. The circuitry permits the host to communicate with one slave at anyone time. The slave can either communicate with the network OR the machinery it controls, but not both at the same time. Information received from the machinery can be transferred to the host along an RS485 line into one RS232 serial port of the host computer. This can then be used and manipulated by the host or any other computer using standard operating systems and programming languages. <IMAGE>

Description

PORTABLE UNIVERSAL TIME AND DISBURSEMENT CAPTURE AND POSTING MODULE.

This invention relates to capturing office expenses and recording time through portable devices and recording the information on a central accounting system.

Computer-based client accounting and time recording systems and disbursesment accounting units have been used, particularly in Legal Practices, for over a decade. There are many competitive products available, especially in the accounting and time recording field. However the products are often expensive, complex systems requiring a high level of staff training and fee earner time, thereby reducing their usefulness.

In the case of disbursement accounting, the cheaper products are simple standalone, non-integrated units which require much human intervention to transfer the information they have collected to the main accounting system. The larger, so called integrated systems are linked via complex networks to dedicated personal computers. These systems are very expensive so are therefore only available to the largest firms, yet still only solve part of the problem.

No single product has been traced which takes all the areas of office expense management, automated time recording and direct posting to the client accounting system, and combines them into a single, integrated system.

According to the present invention there are provided portable data capture units comprising state-of-the-art handheld computers, (which are not part of this invention), held in an enclosure mounting which contains interpretive circuitry enabling the computer to communicate with various office machinery and the network linking it to the main host computer.

The invention connects to the handheld computer via a standard RS232 serial interface. The invention then comprises switching circuitry which allows the handheld computer to communicate either with the host computer or a piece of office machinery, but not both at the same time.

The switching is achieved by reading serial information from the handheld computer and on detection of a software generated code the switch enables communication between the handheld computer and the chosen device.

Once communication of information is complete the handheld computer sends another code which prompts the switch to return to "rest" whereby the handheld computer may communicate with the host computer.

Connection to the host computer is through a RS485 interface enabling the data to be sent along a "twisted pair" as the host computer may be a considerable distance from the handheld computers.

There is no requirement for a conventional network for communication between the handheld computers and the host computer because the latter need only communicate with one hand held machine at any one time, and the handheld machines need not communicate with each other at all. Acccrding to the present invention, therefore, the RS485 will link the output frcm all the handheld computers to the input of the host machine via one "twisted pair". Similarly, the output from the host machine and the input to all the handheld computers will be linked by one "twisted pair". The software generated code of each handheld computer will prevent any communication between the host machine and more than one handheld machine at any one time.

Figure 1 shows the detailed circuitry of the invention.

Referring to the schematic drawing the invention communicates with the RS232 port of the handheld computer via lines 5, 6, 7 and 8. These are data in, data out, RTS and CTS respectively. Units 15, 16 and 17 are interface circuits used to convert between the RS232 signal levels and the O to 5v levels used in the invention's circuit.

The UART converts the serial data to 8 bit parallel codes which are interrogated by the ROM. Particular predetermined codes will cause the output of the ROM to control the latches 22 and 23.

Latch 23 determines whether the handheld computer communicates with the device connected via lines 9, 10, 11 and 12 or listens to data fro:n lines 3 and 4.

Unit 14 is a device that converts bi-phase RS485 signals to the voltage levels used in the circuit. When enabled via the line from Q on Latch 23, its output drives unit 15 and this sends serial data to the handheld computer.

When Unit 18 is enabled Unit 14 is disabled. Unit 18 allows data from the UART to be sent via Unit 15 to the handheld computer. Thus Unit 15 receives data either from the tiART or the RS485 lines but not both.

While Unit 18 is enabled Gate 20 is also enabled, allowing the RTS signal from line 7 to switch the Relay and thus enable the connected device, (be it photocopier, facsimile, printer, or other office. machine).

Pulses from this device, received via lines 11 and 12 and via the Opto-isolator, cause the Monostable to issue pulses to the TX enable input of the UART.

Each pulse causes one serial byte to be sent from the UART. This byte is a serial version of the code presented to the parallel input of the UART from Unit 19 which is a pattern of wire links.

These serial bytes are counted by the handheld computer and represent the number of pulses issued from the device being controlled.

Once the required number of pulses have been received the handheld computer will send a code which will disable the device and re-enable Unit 14.

Unit 13 converts signals from Unit 16 te RS485 output signals on lines 1 and 2. It is enabled via the line from Q of Latch 22.

When the handheld computer receives a particular command code from the Master Computer it responds by sending a code to the UART which in turn produces a parallel output recognised by the ROM which sets Latch 22 and thus enables Unit 13. The handheld computer is then able to "talk" to the Master Computer.

When sufficient Masteríhandheld computer communication has taken place the handheld computer sends another code to the UART which via the ROM resets Latch 22 and disables Unit 13.

Claims

1. An electronic circuit shown in Figure 1 which permits standard computers, requiring no special operating systems, programming languages or communications protocols to be networked together and permit them to control and monitor machinery.

2. An electronic circuit as claimed in Claim 1 wherein, via an RS 485 line, many computers each attached to the electronic circuitry claimed, can be linked to one RS232 serial port on the main host computer using standard communications protocols.

3. An electronic circuit as claimed in Claim 1 and 2 wherein, by means of user designated addresses only one 'slave' computer may communicate with the main computer at any one time.

4. An electronic circuit as claimed in Claim 1,2 and 3 wherein serial information from a slave computer is detected and causes a switch to operate, allowing communication between the computer and either the machinery OR the host computer, but not both at the same time.

5. An electronic circuit as claimed in Claim 1, 2, 3 and 4 wherein data may pass in both directions non-simultaneouslv between the main computer and any one of the slave machines, which cannot communicate with each other at all.

6. An electronic circuit as claimed in Claim 1, 2, 3, 4 and 5 wherein machinery, once enabled by the circuitry, (which is itself controlled by a standard state-of-the-art computer by means of serial information), can be monitored by the computer reading the electrical pulses received from it.

7. An electronic circuit as claimed in Claim 1, 2, 3, 4, 5 and 6 wherein data received from machinery may be interpreted by state-of-the-art computers using their own languages and operating systems and the circuitry on instruction, permits the slave to communicate with the host computer, allowing such data to be read and incorporated into standard systems, databases and programs.