Application Layer. This layer provides access to the business logic according to the calling methods.
Application Layer. The communication port is fully programmable to allow customizing of the data being requested by a DCS or the commands being sent to the turbine. Using MODBUS terminology, there are three types of data: Inputs (not used, same function provided by outputs/coils) Outputs/coils (logic—“Read” & “Write”) Registers (logic & analog—“Read” & “Write”) These data arrays can be programmed to provide the critical turbine data for the DCS. The input array (not used for this application) contains logic data that the DCS can “Read” from but not “Write” to. The output array contains logic data (LDATA) that the DCS can both “Read” and “Write”. The register array contains either analog values (IDATA) (ie. 16 bit quantities) or packed logicals (LDATA) (ie. 16 logicals per register). Registers are “Read” or “Write”. The DCS can send logical commands to the turbine control such as selecting START, STOP, RAISE, LOWER, ETC. A site specific list is created for each job of the appropriate remote command signals that will be accepted from the DCS. An automatic reset of the array protects the turbine against sticky bits or a failed link where a command such as “raise target” could fail activated. The automatic reset forces the DCS to repeatedly send raise/lower commands until the desired level is reached. It is up to the master DCS to control the frequency of data transmissions. Turbine control data is updated at rates between 8 hz and 1 hz depending on how many data points are assigned to the MODBUS list.
Application Layer. The application layer sits between the data store layer and the API layer, and consists in computational modules. In a distributed, virtualized framework, it will be important to distinguish between the application images, i.e., the algorithmic recipes, and their runtime instantiations. Depending on the client demand of an application’s particular service, a virtually unlimited number of instances may thus be spawned from the same image. In our UP-Drive framework, we will employ the Docker standard (xxxxx://xxx.xxxxxx.xxx) in order to represent and manage application images and their instantiations (containers).
