ICP DAS USA HRT-710 User Manual page 21

bit 0: Primary variable out of limits.
[ Note ]
When HART commuication error is reported in the first byte, the second
byte will be 0.
3.3.7 Data
The contents of the data are decided by HART command number.
3.3.8 Check Byte
Every HART frame has a check byte at the last data byte. HART
device can detect error frame by this byte.
HRT-710 User Manual (Version 1.24, June/2015) PAGE: 21