KROHNE CORIMASS MFC 85 Interface EN - Manual (Page 3)

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1. The Krohne SMART System
1.1 Description of operation
The interface for the Krohne Smart system is the current output. Bi-directional information can
be transmitted via the current output cables. The current output signal (0/4 to 20 mA is not
affected because the mean value of the signal containing the digital information is equal to
zero.
The signals are superimposed by means of frequency shift keying (FSK), based on the Bell
202 communication standard. The digital transmission signal is formed from two frequencies:
2200 Hz = “0” and 1200 Hz = “1”.
20 mA 20 mA
MEASURED
VALUE MEASURED
VALUE
0 mA 0 mA
TIME TIME
2200 Hz
“0”
1200 Hz
“1”
CONVENTIONAL SMART FSK MODE
The Smart technology will enable you to utilize its advantages for initial start up, maintenance
work and to change settings. All parameters for new measuring devices (in this case, the
mass flow meter or meters) or those to be changed can be defined and entered into the PC in
the workshop. The stored data can then be downloaded to the mass flow meter and started up
from the control room (via the cable marshalling rack).
The same applies to operation and maintenance. The status of the mass flow meter can be
displayed on-line, or in test mode, the current output can be set to a specific value or values in
order to test the whole circuit. If a converter is replaced, the parameter set from the data base
(PC) can be downloaded into the new converter. This eliminates time consuming data entry
and programming. The possibility of errors being incurred during programming is also
eliminated.
1.2 SMART overview
All Krohne Smart signal converters may be operated via PC. The transmission route may be
up to 1600 m / 5250 ft long. The load between the coupling part of the PC and the converter
output loop should be at least 100 ohms.
Note: This protocol is not compatible with HART

even though it uses a similar method of
communication.