|
Water Industry Telemetry Standard (WITS) is a communications protocol designed for use within the water utility industry between components of a SCADA system. It was developed for communications between a WITS Master Station and its remotely connected WITS Field Devices (for example, Remote Telemetry Units). WITS is based on the DNP3 protocol level2+, and uses DNP3’s generic protocol extension mechanism to define and provide the additional functionality required by water industry users. While initially developed by and for the Water Industry, the WITS protocol is a generic SCADA Communications protocol. The WITS functionality was originally defined in the mid 2000s by the UK water companies via a joint UK Water Industry / equipment vendor’s team.〔(The WITS-DNP3 Telemetry Protocol )〕 During 2011, ownership of the WITS protocol passed into the hands of the (WITS Protocol Standards Association ) for future management and maintenance.〔(Water Briefing announcement on the formation of the WITS Protocol Standards Association )〕〔(Announcement of the formation of the WITS Protocol Standards Association )〕 == Technical Details == WITS adds functionality to the underlying DNP3 protocol :- * Device Profiles * * The characteristics and capabilities of a particular WITS Field Device are defined in a ‘device profile’, which is in XML format. This 'device profile' is read into the WITS Master Station and used to limit what a user can do to that particular Field Device. * Device Configuration * * WITS provides Master Stations with the ability to incrementally change the configuration of Field Devices. This is done by using DNP3 file transfer to send incremental configuration updates to a Field Device. This mechanism provides flexibility for managing the configuration of remote Field Devices from a central location. Examples of configuration changes could be analog input scaling, definition of alarm limits and enabling / disabling inputs. * Information exchange between a WITS Master Station and Field Device * * WITS defines seven DNP3 'Data Sets' for Field Devices to report data to a Master Station and for a Master Station to control a Field Device. These are as follows :- * * for reporting data - change of state or transgression of a limit * * for monitoring the health of a device * * for requesting a device to 'call in' and test a communications path * * for controlling programs sent to a Field Device * * for controlling whether inputs cause events to be sent to the Master Station * Data Logging * * WITS Field Devices can record local data log files. These contain data with a time stamp and retrieved later by a Master Station. The logs are retrieved by means of DNP3 file transfer. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Water Industry Telemetry Standard」の詳細全文を読む スポンサード リンク
|