KROHNE IFC 100 Converter EN - Manual (Page 90)

9
DESCRIPTION OF HART INTERFACE
90
IFC 100
www.krohne.com 07/2010 - 4000041004 - MA IFC 100 R04 en
Description of HART interface
9.1 General description
The open HART ® protocol, which can be used freely, is integrated into the signal converter for
communication.
Devices which support the HART ® protocol are classified as either operating devices or field
devices. When it comes to operating devices (Master), both manual control units (Secondary
Master) and PC-supported workstations (Primary Master) are used in, for example, a control
centre.
HART ® field devices include sensors, converters and actuators. The field devices range from 2-
wire to 4-wire to intrinsically safe versions for use in hazardous areas.
The HART ® data are superimposed over the analogue 4...20 mA signal via FSK modem. This way,
all of the connected devices can communicate digitally with one another via the HART ® protocol
while simultaneously transferring the analogue signals.
When it comes to the field devices and manual control units, the FSK or HART ® modem is
integrated. With a PC, however, communication takes place via an external modem which must
be connected to the serial interface. There are also other connection variants, as shown in the
following connection diagrams.
9.2 Connection variants
The signal converter is a 4-wire device with 4...20 mA current output and HART ® interface.
Depending on the version, the settings and the wiring, the current output can operate as passive
or active output.
• Multi-Drop Mode is supported Multi-Drop Mode is supported Multi-Drop Mode is supported Multi-Drop Mode is supported
In a Multi-Drop communication system, more than 2 devices are connected to a common
transmission cable.
• Burst Mode is not supported Burst Mode is not supported Burst Mode is not supported Burst Mode is not supported
In the Burst Mode a slave device transfers cyclic pre-defined response telegrams, to get a
higher rate of data transfer.
There are two ways of using the HART ® communication:
• as Point-to-Point connection and
• as Multi-Drop connection with 2-wire connection or
as Multi-Drop connection with 3-wire connection.
INFORMATION!
For detailed information about the electrical connection of the signal converter for HART
® , see
the "Electrical connection" section.
.book Page 90 Friday, July 9, 2010 12:29 PM