©National Instruments Corporation4-1FieldPoint FP-3000 User Manual4Block ReferenceThis chapter describes the function blocks and the parameters supported bythe FP-3000.Block OverviewThe FP-3000 consists of a number of blocks. A block is a predefinedsoftware module that runs on an FP-3000 and acts as a fundamentalcomponent of a control system. Each block has a number of parameters thatcan be used to adjust the configuration of that part of the system. These arereferred to as contained parameters. In addition to contained parameters,some blocks have I/O parameters. I/O parameters of different blocks can beconnected together to establish communications between blocks. Eachblock on an FP-3000 has an associated algorithm. There are three types ofblocks: function blocks, transducer blocks, and the resource block.Function BlocksFunction blocks implement the basic control algorithms that make up acontrol strategy. The Fieldbus Foundation has defined a set of tenfundamental (or elementary) function blocks and a set of nineteenadvanced function blocks. The function blocks encapsulate a significantpart of the control system behavior, thereby relieving a host of such tasks.The Fieldbus specification defines the parameters of each function block,how to make each parameter accessible to host system, parameters forconfiguring function blocks, and I/O parameters that can communicate toor from other function blocks in the system. For example, an Analog Input(AI) function block has parameters to scale a transducer value toengineering units. It also has alarm limits that can be configured by a hostor a configurator. The AI detects and reports process alarms such as HI_HI,HI, LO, and LO_LO. The Fieldbus specification does not specify thealgorithm for function blocks. For example, the specification does notdefine the actual equations to use in a PID function block. However, it doesdefine all the parameters needed for configuration and operation of the PID,such as RATE, GAIN, RESET, and MODE. The execution of function blocksand the communication between function blocks on different devices arescheduled deterministically.
