11-01-2011, 03:22 PM
FIELDBUS.ppt (Size: 753.5 KB / Downloads: 82)
Introduction
Fieldbus is an all-digital, two way, multi-drop communication system
Implements distributed control
Control by devices
I/P,O/P and process control devices configured
Used for
Process control
Process monitoring
Devices
Devices-field devices or host
device tag
string name
Unique on n/w
configurable attribute
type of device
Address
ID
serial no.
Unique to the device
assigned by manufacturer
not configurable
Types of devices
3 types of devices on H1 n/w
Link master
Controls commn. traffic on a link by scheduling
An interface board in PC, dcs, valve, pt
FB operate independently of a cp sys.because of linkmasters
Have processing and controlling capability
Link Active Scheduler(LAS)-currently active link master
Publishes time information
Grants permissions to devices
Basic devices
not capable of scheduling commn.
Cannot become LAS
H1 bridges
Connects links together into a spanning tree
H1 & HSE
2 communication protocols
H1(transmits at 31.25Kb/s connecting field devices)
HSE(High Speed Ethernet uses 10 or 100Mbps Ethernet as the physical layer)
H1 links interconnected by H1 data link bridges
HSE to H1 interconnections by linking devices