Rockwell Automation PLC-5 Fieldbus Solutions for Integrated Architecture User Manual - Manual (Page 62)

Publication 1757-UM006A-EN-P - May 2002
2-18 Integrating Fieldbus into Rockwell Automation Logix System
The status byte structure consists of a 2-bit quality, most significant bit,
field; a 4-bit substatus field; and a 2-bit limits, least significant bit,
field. The following table provides a breakdown of bit assignments for
general reference. The value of the quality field determines the
applicable substatus field indication.
Fieldbus Status Indications
See Appendix B for list of possible display indications associated with
a given fieldbus status.
Table 2.B Breakdoun of bit assignments
Bit Quality Substatus, if Quality field is Limits
BAD UNCERTAIN GOOD
(Non-Cascade)
(1)
GOOD (Cascade)
(1)
0 BAD Data Quality Non-Specific Non-Specific Non-Specific Non-Specific No Limits
1 UNCERTAIN Data
Quality Configuration Error Last Usable Value Active Block Alarm Initialization
Acknow-ledge (IA) Low Limit
2 GOOD
(Non-Cascade)
Data Quality Not Connected Substitute Active Advisory
Alarm Initialization Request
(IR) High Limit
3 GOOD (Cascade)
Data Quality Device Failure Initial Value Active Critical
Alarm Not Invited (NI) Constant
4 Sensor Failure Sensor Conversion
Not Accurate Unacknow-ledged
Block Alarm Not Selected (NS)
5 No Communication, with
Last Usable Value Engineering Unit
Range Violation Unacknow-ledged
Advisory Alarm Do Not Select (DNS)
6 No Communication, with
no Last Usable Value Sub-Normal Unacknow-leged
Critical Alarm Local Override (LO)
7 Out-Of-Service Fault-State Active (FSA)
8 Initiate Fault-State (IFS)
(1) The Good (non-cascade) substatus is used by output connections for fieldbus blocks such as Analog Input and Discrete Input. The Good (cascade) substatus is used by
output connections for fieldbus blocks such as PID. Both of these substatuses are converted to the single ProcessLogix data quality of Good.