7
1.4
Intrinsic Safety
The IEC 61158 physical layer supports Intrinsic Safety (IS)
applications with bus-powered devices. To accomplish this,
an IS barrier or galvanic isolator is placed between the
power supply in the safe area and the device in the
hazardous area.
IEC 61158 also supports the Fieldbus Intrinsically Safe
Concept (FISCO) model which allows more field devices in
a network. The FISCO model considers the capacitance and
inductance of the wiring to be distributed along its entire
length. Therefore, the stored energy during a fault will be
less and more devices are permitted on a pair of wires.
Instead of the conservative entity model, which only allows
about 90 mA of current, the FISCO model allows a maxi-
mum of 110 mA for Class II C installations and 240 mA
for Class II B installations.
FISCO certifying agencies have limited the maximum
segment length to 1000 meters because the FISCO model
does not rely on standardized ignition curves.
The Model R86 PA is available with entity IS, FISCO IS,
and FNICO non-incendive approvals.
2.0
Function Blocks
2.1
Overview
The Pulsar Model R86 Non-Contact Radar Level
Transmitter operates at 26 GHz. Refer to Bulletins 58-103
and 58-603 for more detailed information on the Pulsar
product family.
The Pulsar Model R86PA is a Non-Contact level transmitter
with twelve PROFIBUS PA
™
Blocks (one Physical Block,
three Transducer Blocks, and eight Analog Input blocks).
The idea of Function Blocks, which a user can customize
for a particular application, is a key concept of fieldbus
topology. Function Blocks consist of an algorithm, inputs
and outputs, and a user-defined name.
The TRANSDUCER block output is available to the
network through the ANALOG INPUT blocks.
The ANALOG INPUT blocks (AI) take the TRANSDUCER
block measured values and makes them available as an
analog value to the network. The AI blocks have scaling
conversion, filtering, and alarm functions.
58-645 Pulsar® Model R86 Non-Contact Radar Transmitter – PROFIBUS PA Output