Rapid transport service in a network to peripheral device servers

• US 7,680,944 B1
• Filed: 02/27/2004
• Issued: 03/16/2010
• Est. Priority Date: 02/28/2003
• Status: Expired due to Fees

• Current Assignee: Pepperl + Fuchs GmbH
• Original Assignee: Comtrol Corporation (Pepperl+Fuchs Se)
• Inventors: Edwards, Grant B., Taghizadeh, Ehassan, Robideau, Kurt, Erler, Stephen P.
• Primary Examiner(s): Srivastava; Vivek
• Assistant Examiner(s): Pollack; Melvin H
• Application Number:
  US10/788,959
• Time in Patent Office: 2,209 Days
• Field of Search: 709/203, 709/216, 709/223, 709/224, 709/227, 709/230, 709/236, 709/249, 709/250, 719/314, 719/321, 719/327, 719/328, 710/15, 710/23, 710/53, 710/54, 710/71, 710/112, 370/366, 370/395.72, 370/412, 370/413, 340/825.62, 341/100, 341/101
• US Class Current: 709/230
• CPC Class Codes: G06F 13/102 where the programme performs an interfacing function, e.g. device driver G06F13/105 takes precedence; scheduling within device drivers G06F9/52; contention policies within device drivers G06F9/4881
• CPC Class Codes: G06F 13/387 for adaptation of different data processing systems to different peripheral devices, e.g. protocol converters for incompatible systems, open system
• CPC Class Codes: H04Q 2213/13093 Personal computer, PC
• CPC Class Codes: H04Q 2213/13103 Memory
• CPC Class Codes: H04Q 2213/13204 Protocols
• CPC Class Codes: H04Q 2213/13389 LAN, internet

Abstract

A low latency peripheral device sharing system has a host computer with an operating system, a kernel memory buffer, applications, device specific drivers, and a peripheral server driver. The server driver intercepts function calls invoking the local serial ports, and passes standard serial data from the application to a local area network. A device server on the local area network reads the data using a hybrid read block (semi-blocking read), and writes the data to the FIFO registers of the serial device and the remaining data to a queue for the serial device. Finally, the device server times the serial data and returns an intercharacter interval timer flag to the host computer to terminate a read operation.

Claims

1. A device server system comprising:

serial devices;

a device server for connecting the serial devices to a local area network, the device server comprising;

a FIFO register associated with each serial device, and

a memory queue associated with each serial device;

driver software installed on a host computer with an operating system that is connected to a local area network, the driver software for directing serial port data onto the local area network; and

firmware installed on the device server for facilitating communication between the host computer and a selected one of the serial devices, wherein the firmware directs the serial port data received from the remote computer to the selected one of the serial devices, and wherein the firmware writes portions of the received serial port data to the FIFO register associated with the selected one of the serial devices, if the memory queue associated with the selected one of the serial devices is empty, before writing remaining data of the received serial port data to the memory queue associated with the selected one of the serial devices.

2. The system of claim 1 wherein, when an application on the host computer invokes a function involving a serial device, the driver software transfers data intended for the serial device to a transport protocol of the host computer for transmission to the device server.

3. The system of claim 1 further comprising:

application software installed on the device server for handling device specific flags and timeouts.

4. The system of claim 1 wherein the device server has an operating system and the firmware application functions within the operating system.

5. The system of claim 1 wherein the FIFO registers are located in a serial chip associated with each serial device.

6. The system of claim 1 wherein the driver software utilizes a transport protocol to direct the serial port data onto the local area network.

7. The system of claim 6 wherein the local area network is an Ethernet network and wherein the transport protocol utilizes Ethernet hardware addresses to route the serial data over the local area network.

8. A system for connecting serial devices to a local area network comprising:

a device server in communication with the local area network, the device server comprising;

serial connectors for linking one or more serial devices to the device server;

an operating system; and

applications running on the operating system for coordinating communications between the operating system, the local area network, and the serial device;

a serial driver installed on a host computer and for mediating between host application software and host operating system software installed on the host computer, the host computer being in communication with the local area network, wherein the serial driver transmits serial data from the host application software over the local area network to a selected serial device linked via one of the serial connectors to the device server;

wherein the applications transfer one or more bytes of the serial data from a buffer of the device server to a memory queue associated with the selected serial device when the one or more bytes appears in the buffer without waiting for a specified byte count or a polling period.

9. The system of claim 8 wherein the applications for transferring the serial data transfer serial data as soon as data is available up to a predefined number of bytes.

10. The system of claim 8 wherein the serial driver on the host computer uses a transport protocol for transmitting the serial data over the local area network.

11. The system of claim 10 wherein the transport protocol is TCP.

12. The system of claim 10 wherein the local area network is an Ethernet network and wherein the transport protocol utilizes Ethernet hardware addresses to route the serial data over the local area network.

13. A system for connecting serial devices to a network, the system comprising:

host driver software installed on a host computer connected to the network, wherein the host driver software interfaces with host application software and host operating system software, the host operating system software having a serial port application program interface, wherein the host driver software receives serial port data over the network using the serial port application program interface, the serial port application interface comprising;

an intercharacter interval timer that measures a time interval between the end of a stop signal of one character and the beginning of a start signal of a next character; and

an intercharacter interval setting;

wherein the application program interface terminates a read operation when the time interval measured by the intercharacter interval timer exceeds the intercharacter interval setting

and

a device server connected to the network and in electrical communication with one or more serial devices, the device server comprising;

an intercharacter interval timer that measures a time interval between the end of a stop signal of one character and the beginning of a start signal of a next character; and

an intercharacter interval setting;

wherein the device server receives the serial port data over the network and measures an intercharacter interval corresponding to the intercharacter interval timer setting of the serial port application program interface, and wherein the device server returns a flag to the host computer when the time interval measured by the intercharacter interval timer exceeds the intercharacter interval setting, and wherein the flag signals the host computer that a read operation has terminated.

14. A method for facilitating communication between a host computer and a serial device over a network, the method comprising:

transmitting data in a standard serial port format over a local area network to a selected serial device;

receiving the data at a device server connected to the network, the device server having one or more serial ports connected to one or more serial devices, one of the one or more serial devices being the selected serial device;

storing the received data temporarily in a buffer;

reading the received data from the buffer;

writing the read data to a FIFO register associated with the selected serial device, such that if the FIFO register is empty, the read data is written to the FIFO register until the FIFO register is full and the remaining data is written to a memory queue associated with the selected serial device.

15. The method of claim 14 wherein the step of transmitting comprises:

encoding the data into frames; and

placing the frames onto the local area network.

16. The method of claim 14 wherein the serial devices are connected to the device server via serial cables.

17. The method of claim 14 wherein the step of transmitting comprises:

converting information from an application on the host computer into the data in the standard serial port format using a device specific serial driver;

transferring the data in kernel space on the host computer from a serial port buffer to a transport buffer using a server driver;

encoding the data in the transport buffer; and

transmitting the encoded data onto the local area network.

18. The method of claim 17 wherein the step of receiving comprises:

decoding a received encoded data; and

storing the decoded data in the buffer.

19. A method for eliminating synchronization latencies in a remote device server for facilitating communication between a host computer and a selected serial device, the method comprising:

receiving a read-operation-ending intercharacter interval value corresponding to the selected serial device over a network link from the host computer to the remote device server;

transmitting data in a standard serial port format over a network link from the selected serial device to the remote device server;

receiving the data with the remote device server;

measuring an intercharacter interval of the data with the remote device server by comparing the end of a stop signal of one character and the beginning of a start signal of a next character;

transmitting the data over the network link from the remote device server to the host computer;

transmitting a flag over the network link from the remote device server to the host computer when the intercharacter interval of the data from the selected serial device exceeds the read-operation-ending intercharacter interval value corresponding to the selected serial device;

receiving the flag with the host computer; and

terminating a read operation at the host computer.