Slave device

{
  "publication_number": "US10346332B2",
  "country": "US",
  "kind": "B2",
  "title": "Slave device",
  "abstract": "When a data request is sent from a master device in master-slave communication, a slave device determines whether a piece of data requested by the data request among data stored on the slave device side has been updated after previous transmission of the piece of data. If the piece of data has been updated, the slave device sends the updated piece of data as a response to the data request. If the piece of data has not been updated, the slave device suspends a response to the data request. Thus, a communication system is built which can reduce network processing load and the volume of communication data in the case where the master device periodically acquires data from the slave device.",
  "claims": [
    "1. A slave device for performing master-slave communication with a master device and, in response to a data request sent from the master device, sending data requested by the data request as a response, the slave device comprising: a data section for storing data; a functional operating section for updating data stored in the data section; a data update management section for managing an update of data stored in the data section; and a command analysis section for, in response to a data request sent from the master device, determining whether a piece of data requested by the data request among data stored in the data section has been updated after previous transmission of the piece of data, sending the updated piece of data as a response to the data request if it is determined that the piece of data have been updated after the previous transmission, and suspending a response to the data request if it is determined that the piece of data has not been updated after the previous transmission, wherein while the command analysis section suspends the response to the data request, the command analysis section is configured to monitor whether the data stored in the data section is updated, in response to the data stored in the data section being updated within a predetermined period of time after the data request is sent from the master device, the command analysis section is configured to read the updated data stored in the data section and send, as the response to the data request, the updated data to the master device, and in response to the data stored in the data section not being updated within the predetermined period of time after the data request is sent from the master device, the command analysis section is configured to send, as the response to the data request, the unupdated data stored in the data section to the master device.",
    "2. The slave device according to claim 1, wherein the data update management section is configured to store a data update flag which is turned ON when the data stored in the data section is updated, and in response to the data update flag corresponding to a piece of data stored in the data section being ON, the command analysis section is configured to determine that the piece of data has been updated after the previous transmission.",
    "3. The slave device according to claim 1, wherein the data update management section is configured to store, as sent data, a data value which a piece of data stored in the data section has had at the previous transmission, and in response to a piece of data stored in the data section being different from the sent data corresponding to the piece of data, the command analysis section is configured to determine that the piece of data has been updated after the previous transmission.",
    "4. The slave device according to claim 1, wherein the command analysis section is configured to determine whether a piece of data requested by the data request among data stored in the data section has been updated after the previous transmission of the piece of data, in accordance with operation mode.",
    "5. The slave device according to claim 1, wherein the command analysis section is configured to determine, based on a timeout period between the master device and the slave device, a period of time during which a response to the data request is suspended."
  ],
  "description_excerpt": "The present invention relates to a slave device, and particularly relates to a slave device which determines information transmission timing in master-slave communication.\n\nWith the popularization of the Internet of Things (IoT) technology, collecting sensor-acquired information and internal information through networks has increasingly become active. In networks in factories, a method has generally been widely used in which a master device (CNC or PC) periodically requests slave devices (such as sensors) to read out data to collect data.\n\nMost standards for master-slave communication performed between a master device and a slave device generally support both of read and write operation by the master device with respect to the slave device. In actual operation, however, some devices (such as IO devices) perform both read and write operations, but there are many cases where a slave device (such as a sensor or a counter) assumes that a master device performs one-way data read operations, or where a master device sends only data read-out requests for data collection (such as an operation management system).\n\nIn such master-slave communication, in the case where a master device periodically collects data from a slave device, the maximum value of the time (information transmission time) elapsed after a change occurring in data possessed by the slave device before the master device knowing the change depends on the time interval (polling interval) at which the master device sends a data request to the slave device, as shown in FIG. 4.",
  "cpc": [
    "G06F 13/362",
    "G06F 11/3079",
    "G06F 13/38",
    "G06F 13/42",
    "G06F 9/44505",
    "H04L 1/22",
    "H04L 12/403",
    "H04L 67/12"
  ],
  "ipc": [
    "G06F 13/362",
    "G06F 9/445",
    "G06F 11/30",
    "G06F 13/38",
    "G06F 13/42"
  ],
  "assignees": [
    "Fanuc Corp"
  ],
  "inventors": [
    "Masaki Tanabe"
  ],
  "filing_date": "2017-10-05",
  "publication_date": "2019-07-09",
  "grant_date": "2019-07-09",
  "priority_date": "2016-10-12",
  "application_number": "US-201715725479-A",
  "family_id": "61696086",
  "cited_by_count": 4,
  "citations": [
    "US4167730A",
    "US4589081A",
    "US5274838A",
    "JPH07147582A",
    "US5905523A",
    "US5706210A",
    "US6006148A",
    "US20070058556A1",
    "US8260872B1",
    "US20170092114A1"
  ]
}