ProSoft Technology MVI69-HART - Manual (Page 42)

Module Configuration MVI69-HART ♦ CompactLogix Platform
User Manual HART Multi-drop Master Communication Module
Page 42 of 169 ProSoft Technology, Inc.
March 29, 2012
2.3 Hart Command Examples
This section describes two examples that shows how to configure HART
commands. The first example shows a read command (function code 3 - READ
DYNAMIC VARIABLES) and the second example shows a write command
(function 34 - WRITE DAMPING VALUE).
2.3.1 Example of HART Command Function 3
The following example shows how to configure a command function 3 (READ
DYNAMIC VARIABLES) to read the process variables from the HART slave
device. According to the HART specification, this command will return four
floating-point variables:
Word High Byte Low Byte
0 Current (mA)
1
2
Primary Variable
3
4
Second Variable
5
6
Third Variable
7
8
Fourth Variable
9
The command also returns the following integer data:
Word High Byte Low Byte
0 Status Word
1 Primary Variable Units Code Second Variable Units Code
2 Third Variable Units Code Fourth Variable Units Code
So, this command will return the following number of words:
Parameter Data Type Direction Number of
Words Database
Address
(this example)
Variable Results Floating Point Read from slave to MVI 10 240 (word address)
Status/Unit Codes Integer Read from slave to MVI 3 290 (word address)