HART Commands - Ifea

Command 48 Example
� We know that Bit-OFF is normal and Bit-ON is abnormal or information available
� We do not know what the status bit means! Each Bit and it’s
associated description is contained in the vendor DD file. DD -Device Descriptor file
Example: The Honeywell STT250 temperature transmitter uses three of these bytes, as follows:
Byte-0 Critical Byte-1 Non-Critical Byte-2 Information
Bit DEVSPCBIT DD-Descriptor Bit DEVSPCBIT DD-Descriptor Bit DEVSPCBIT DD-Descriptor
0 [0] undefined
1 [1] Hardware
Failure
2 [2] Input Open.
3 [3] NVM Calib
Failed
4 [4] NVM Conf failed
5 [5] undefined
6 [6] undefined
7 [7] undefined
0 [8] CJ Over Temp
1 [9] undefined
2 [10] Input out of Spec
3 [11] Output Saturated
4 [12] In Output Mode
5 [13] undefined
6 [14] undefined
7 [15] User Correct
Active
0 [16] Suspect Input
1 [17] undefined
2 [18] undefined
3 [19] undefined
4 [20] undefined
5 [21] undefined
6 [22] undefined
7 [23] 4 wires
Configuration
� Status bits can be used in CM’s and graphics by using the TAG/Name. DEVSPCBIT[##] format!
42 HONEYWELL September 19, 2012
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