Rockwell Automation 1758-RTU202 DataSite Software User Manual FRN 1.2 - Manual (Page 58)

Publication 1758-UM002D-EN-P - October 2010
58 DataSite Configuration Settings Utility (DS Settings)
Here is an example of a HART configuration list:
Understand HART Commands
Some of the variables read from HART equipment are 32-bit floating-point
values. Every floating-point value is stored in two continuous data registers.
The higher 16 bits of this value will be stored in the register with a higher
address and the lower 16 bits of this value will be stored in the register with a
lower address. For example, if a 32-bit double precision IEEE floating point
number, such as 1234.5678 is to be stored, two registers, such as register 40108
and register 40109 can be combined to store the number. In hexadecimal,
1234.5678 is 449A 552B. The DataSite controller will store 449A in register
40109 and 522B in register 40108.
Registers Used in HART Commands
The following table lists the number of registers used in each HART command
for the four register types, namely Send, Return, Unit and HART state.
Number of registers used in each HART command
Command Description Number of registers
Send register Return register Unit register HART state
register
0 Read Unique Identifier 0 10 0 2
1 Read Primary Variable 0 2 1 2
2 Read P. V. Current And Percent Of Range 0 4 0 2
3 Read Dynamic Variable And P. V. Current 0 10 4 2
15 Read Transmitter Variables 0 10 0 2
33 Read Primary Variable Output Information 4 12 4 2
35 Write Primary Variable Range Values 9 0 0 2
38 Reset Configuration Changed Flag 0 0 0 2
40 Enter/Exit Fixed Primary Variable Current
Mode 4 0 0 2
44 Write Primary Variable Units 1 0 0 2