Control Valves Chemical attack Problems
Corrosive chemicals may attack the metal components of control valves if those components are not carefully selected for the proper service. Control Valves Chemical attack A close-up photograph of a…
FF Function block Modes
All FF function blocks must support multiple modes of operation, describing how the block should execute its intended function. Several different function block modes are commonly found for FF function…
FF Signal Status
FF function block programming bears a strong resemblance to analog function block circuit design, where specific tasks are divided up into discrete elements, those elements connected together to form a…
Foundation Fieldbus Standard Function Blocks
The FF standard specifies many different function blocks for the construction of control algorithms. Ten of them are considered “basic” FF function blocks: AI – Analog Input AO – Analog…
H1 FF Data Link layer
Like so many other industrial data networks, FOUNDATION Fieldbus is an “unswitched” or “broadcast” type of network. This means all data transmissions by all devices on a network are sensed…
H1 FF Physical layer
Layer 1 of the OSI Reference Model is where we define the “physical” elements of a digital data network. The H1 FF network exhibits the following properties: Two-wire (ungrounded) network…
Flow Standards
Continuous flow measurement are inferential, that is, we measure flow indirectly by measuring some other variable (such as pressure, time) directly.
Analytical Standards
An analyzer measures intrinsic properties of a substance sample such as its density, chemical content, or purity. Whereas the other types of instruments discussed in this chapter measure quantities incidental…
Foundation Fieldbus Logics
There is usually some freedom of choice in where various function blocks may be located in a FF segment. Take for example the following flow control loop, where a flow…
FF Function Blocks
Data-processing modules within FF systems are known as function blocks. Sometimes these blocks serve merely to catalogue data, while in other instances the blocks execute specific algorithms useful for process…
