 | M&M FDT 1.2.1 Online Specification |
Interfaces and Methods - Schemas - FDT Specification - Quicklinks - Abbreviations
6.1 DTM Peer To Peer Communication
6.1.1 Establish a Connection between DTM and Device
6.1.2 Asynchronous Connect
6.1.3 Asynchronous Disconnect
6.1.4 Asynchronous Transaction
6.2 Nested Communication
6.2.1 Generate Systemtopology
6.2.2 Establish a Connection between DTM and Device
6.2.3 Asynchronous Transaction
6.3 Topology Scan
6.3.1 Scan Network
6.3.2 Cancel Topology Scan
6.3.3 Provisional Scan Result Notifications
6.3.4 Scan for Communication Hardware
6.3.5 Manufacturer specific Device Identification
6.4 Registration of Protocol Specific FDT Schemas
6.5 Configuration of a Fieldbus Master
6.6 Starting and Releasing Applications
6.7 Channel Access
6.8 DCS Channel Assignment
6.9 Printing of DTM Specific Documents
6.10 Printing of Frame Application Specific Documents
6.11 Propagation of Changes
6.12 Locking
6.12.1 Locking for Non Synchronized DTMs
6.12.2 Locking for Synchronized DTMs
6.13 Instantiation and Release
6.13.1 Instantiation of a New DTM
6.13.2 Instantiation of an Existing DTM
6.13.3 Instantiation of a DTM User Interface
6.13.4 Release of a DTM User Interface
6.14 Persistent Storage of a DTM
6.14.1 State machine of instance data
6.14.1.1 Modifications
6.14.1.2 Persistence
6.14.2 Saving Instance Data of a DTM
6.14.3 Reload of a DTM Object for Another Instance
6.14.4 Copy and Versioning of a DTM Instance
6.15 Audit Trail
6.16 Comparison of Two Instance Data Sets
6.16.1 Comparison Without User Interface
6.16.2 Comparison With User Interface
6.17 Failsafe Data Access
6.18 Set or Modify Device Address With User Interface
6.19 Sets or Modifies Known Device Addresses Without User Interface
6.20 Display or Modify All Child Device Addresses With User Interface
6.21 Device Initiated Data Transfer
6.22 Starting and Releasing DTM User Interface in Modal Dialog
6.23 Parent Component Handling Redundant Slave
6.24 Initialization of a Channel ActiveX Control
6.24.1 Supports IFdtChannelActiveXControl2
6.24.2 Does Not Support IFdtChannelActiveXControl2
6.25 DTM Upgrade
6.25.1 Saving Data from a DTM to be Upgraded
6.25.2 Loading Data in the Replacement DTM
6.26 Usage of IDtmSingleDeviceDataAccess::ReadRequest / Write Request
6.27 Instantiation of DTM and BTM
6.12 Locking
Within a multi user environment it is common, that more than one DTM have access to the same data set. To synchronize DTMs which are started by several users on different workplaces FDT provides a locking mechanism. Target for this event mechanism is that only one DTM has read/write access to the data set. All other DTMs have read access only.
For this reason a DTM must lock it’s data set only if required and only during modification of the data. After the instance data is saved by the Frame Application and is not further under modification the DTM must unlock it’s data set immediately to enable concurrent access to the device data by other DTM instances within a multiuser environment.
- Before opening an ActiveX the DTM must try to lock the dataset. If successful all user input fields can be enabled, in the other case user input fields must be disabled. After closing all ActiveX controls in case of a locked datatset the DTM should request to save the dataset and unlock the data set after Frame Application has saved the dataset.
- Before an upload the DTM must also try to lock the dataset, after upload DTM should call IFdtContainer::SaveRequest() and unlock dataset after Frame Application has saved dataset.
- A DTM can only unlock the dataset if no user interface with write-access is opened.
- If a DTM locks it’s dataset after instantiation and unlocks during e.g. a IDtm::PrepareToRelease() this DTM is not suitable for use within a multiuser environment.
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Last updated 2015-02-05 15:17
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