CNGmass DCI
Operation
Hauser
31
5.4.3
Device and process variables
Device variables
The following device variables are available using the HART protocol:
Process variables
At the factory, the process variables are assigned to the following device variables:
• Primary process variable (PV)
→
Mass flow
• Secondary process variable (SV)
→
Totalizer 1
• Third process variable (TV)
→
Density
• Fourth process variable (FV)
→
Temperature
!
Note!
You can set or change the assignment of device variables to process variables using
Command 51
5.4.4
Universal/Common practice HART commands
Code (decimal)
Device variable
Code (decimal)
Device variable
0
OFF (unassigned)
8
Reference density
2
Mass flow
9
Temperature
5
Volume flow
250
Totalizer 1
6
Corrected volume flow
251
Totalizer 2
7
Density
252
Totalizer 3
Universal Commands
Command No.
HART command / Access type
Command data
(numeric data in decimal form)
Response data
(numeric data in decimal form)
0
Read unique device identifier
Access type = read
none
Device identification delivers information on the device and the
manufacturer. It cannot be changed.
The response consists of a 12-byte device ID:
– Byte 0: Fixed value 254
– Byte 1: Manufacturer ID, 17 = Hauser
– Byte 2: Device type ID, e.g. 85 = CNGmass DCI
– Byte 3: Number of preambles
– Byte 4: Universal commands rev. no.
– Byte 5: Device-spec. commands rev. no.
– Byte 6: Software revision
– Byte 7: Hardware revision
– Byte 8: Additional device information
– Byte 9-11: Device identification
1
Read primary process variable
Access type = read
none
– Byte 0: HART unit code of the primary process variable
– Bytes 1-4: Primary process variable
Factory setting:
Primary process variable = Mass flow
!
Note!
• You can set the assignment of device variables
to process variables using Command "51".
• Manufacturer-specific units are represented using the HART unit
code "240".