KROHNE UFC 500 HART - Manual (Page 11)

HARTô Smart Communications Protocol
UFC500 Command Specification Rev: 2.0 Release Date: 9 Jun 2001
© 2001 KROHNE Mefltechnik D-47058 Duisburg Page 11
6. Additional Universal Command Specifications
This section contains information pertaining to those commands that require clarification.
6.1 Command #0 Read Unique Identifier
Device Identification Number (Data bytes #9..#11 of response packet) is preserved in the instrument as a 10-bytes
ASCII number (Service Fct. 5.1.4, ìSerial Nmbî). Hence only three (low significant) bytes of this number (after it is
transferred to digital value) are ìvisibleî to HARTÆ-requester.
6.2 Command #2 Read P.V. Current And Percent Of Range
If the Primary Variable is assigned to Direction variable, the Percent of Range value is replied as Not-a-Number.
6.3 Command #6 Write Polling Address
This revision of the transmitter has an active current output and is not conformant with multidrop mode hardware
requirements. Still the command can be used in point-to-point communication. The multidrop software support will not
be changed when the further firmware release meets all specification restrictions.
On entering of multidrop mode shutdown of device current is performed: a fixed range of 4-20 mA is set and the
function of Primary Variable current output is switched ìOffî. Refer to Commands #50, Read Dynamic Variable
Assignments, #138, Read Analog Output Function, and #140, Read Current Output Parameters.
When multidrop mode is exited, all the parameters of the current output are restored.
6.4 Command #14 Read Primary Variable Sensor Information
Sensor serial number is not stored within device and therefore is responded as Ñnot applicable to deviceì (zero value).
Sensor parameters depend on the meter diameter and should be reread if the latter is changed.
6.5 Command #15 Read Primary Variable Output Information
Upper Range Value depends on the meter diameter. When the latter is changed, Upper Range Value for FlowRate will
be automatically corrected if needed. In the last case bus master will be prompted about compulsory changes in
correlated parameters via Warning-type Response Codes (refer to Command #131, Write Meter Diameter). No such
correction is done when Primary Variable is set to TransitTime. In the latter case meter-conformant Range Values
should be assigned via Command #159, Write Transmitter Variable Range Values.
Write Protect Code variable (Data byte #15 of response packet) depends on the setting made for device variable Entry
Code, Menu 3.5.2. It can be altered via Command #150, Enable/Disable Password Protection.