INTELLIBUS
Number : NR 1157
Revision : B
Page 7/19
Instructions for start-up
the actuator answers with a PR, the LAS adds the actuator to the live list and
confirms its addition by sending the actuator a Node Activation message.
4.1.2 Function Block
A function block is like a black box inside the INTELLIBUS FF interface with input
and output parameters. Function Block is used by the control system to
communicate through the Fieldbus.
Function block name:
Discrete input (DI) (input in a fieldbus view) For example: valve is open
Discrete output (DO) For example: close the valve
Analog input (AI) For example: valve is 50% open
Analog output (AO) For example: close the valve at 30%
In each function block there is a list of parameters available (see § 4)
An other Function Block is the Proportional/ Integral / Derivative (PID) to perform
control loop (see § 6).
4.1.3 Transducer Block
The Transducer Block contains information not used for the process such as
manufacture date, dead band setting, opening and closing torque/position curve.
(see §5 )
4.1.4 Device description
To achieve interoperability Device Description (DD) technology is used. The DD is
like a “driver” for a printer. L.Bernard supply the Device Description for the
INTELLIBUS FF interface.
4.2 Foundation Fieldbus technology
4.2.1 Fieldbus Signaling
The transmitting device de/- 10mA at
31.25 kbit/s into a 50 ohm equivalent load to
create a 1.0 volt peak-to-peak voltage modulated
on top of the direct current supply voltage. The
DC voltage can range from 9 to 32V.
The maximum DC current available depends of
the fieldbus power supply.
4.2.2 Maximum cable length
The Fieldbus cable coming from a PLC is connected to the first actuator then the Fieldbus
cable links this actuator with the next one and so on. All actuators are connected to the
line one after the other until the last one. No return to the PLC is required.
The 31.25kbit/s fieldbus allows ramifications or “spurs” but with restrictions
Cable length = Trunk total spur lengths
Maximum length = 1900m (6200ft) with “Type A” cable
Devices Max total spur length
25-32
No spur
No spur
19-24
30m
100ft
15-18
60m
200ft
13-14
90m
300ft
1-12
120m
400ft
voltage
time
Fieldbus messages