Appendix B. Command Format
The HART data format of MB address is divided into the “Normal” and “Simple” format.
1. Normal format :
When read / write HART data by Modbus, the MB data format is HART standard command
format.
2. Simple format :
When read / write HART data by Modbus, the MB data format is simple format (omit the
“Response Code” and “Unit” data). In this mode, the HMI or SCADA software can read or write
HART data easily. Now, it only supports HART command number 1, 2 and 3.
The simple format of HART command is shown as below:
(1) Command 1: (Read Primary Variable)
Request data bytes: none
Response data bytes: 4
Index
Format
Description
Byte 0~3
float
Primary Variable
(2) Command 2: (Read P.V. Current and Percentage of Range)
Request data bytes: none
Response data bytes: 8
Index
Format
Description
Byte 0~3
float
Primary Variable Current
Byte 4~7
float
Primary Variable Percentage of Range
(3) Command 3: (Read Dynamic Variables and P.V. Current)
Request data bytes: none
Response data bytes: 20
Index
Format
Description
Byte 0~3
float
Primary Variable Current
Byte 4~7
float
Primary Variable
Byte 8~11
float
Secondary Variable
Byte 12~15
float
Tertiary Variable
Byte 16~19
float
4th Variable
HRT-710 / HRT-310 User Manual
Version 1.31
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