Operating Instructions - VEGADIS 62 -

9 Supplement9.2 HART communicationThe HART protocol operates with the technology of the frequency shift keying (FSK = frequency shiftkeying) based on the data communication standard Bell 202. The digital signal is generated out of thefrequencies 1200 and 2200 Hz representing each the bit information 1 and 0. Sinus curves with thesefrequencies are superimposed to the direct current in the wire pair of the field device. The averagevalue of the superimposed signal is zero. Hence the 4 … 20 mA signal is not influenced by the digitaldata transmission.Commands when transmittingDuring transmission, only the long address format is used which is supported by all sensors as ofHART revision 5.Command no. Command name Description0 Read UID For determination of the UID from the polling address15 Read output information To update the scaling of the display after ZERO orSPAN34 Write damping value -35 Write range values Adjustment of the transmitter scaling36 Set upper range value SPAN button37 Set lower range value zero button44 Write PV units Adjustment of the transmitter unit54 Read Transmitter VariableInformationTo read out the adjusted dampingCommand during receptionOnly messages are received the return address of which correspond with adjusted polling address orthe determined UID.Command no. Command name Description1 Read primary variable To check the adjusted measuring unit3 Read current & 4 vars To check the adjusted measuring unit15 Read output information Accept transmitter scaling35 Write range values Transmitter scaling by control room38 VEGADIS 6236469-EN-100514