National Instruments 370578B-01 用户手册

C

Celsius.

Cable

A number of wires and shield in a single sheath.

Channel

A pin or wire lead to which you apply or from which you read the 
analog or digital signal.

Communication stack

Performs the services required to interface the user application to the 
physical layer.

Control loop

A set of connections between blocks used to perform a control 
algorithm.

CPU

Central processing unit.

Data Link Layer

The second-lowest layer in the ISO seven-layer model (layer two). 
The Data Link Layer splits data into frames to send on the physical 
layer, receives acknowledgment frames, and re-transmits frames if 
they are not received correctly. It also performs error checking to 
maintain a sound virtual channel to the next layer.

DD

See Device Description. 

Descriptor

A number returned to the application by the NI-FBUS 
Communications Manager, used to specify a target for future 
NI-FBUS calls.

Device

A sensor, actuator, or control equipment attached to the Fieldbus.

Device address

A memory address that you use to access a device in a computer 
system.

Device Description

A machine-readable description of all the blocks and block 
parameters of a device.

Device ID

An identifier for a device that the manufacturer assigns. 
No two devices can have the same device ID.

Device tag

A name you assign to a Fieldbus device.

Directory

A structure for organizing files into convenient groups. A directory 
is like an address showing where files are located. A directory can 
contain files or subdirectories of files.

Driver

Device driver software installed within the operating system.