Rockwell Automation PLC-5 Fieldbus Solutions for Integrated Architecture User Manual - Manual (Page 61)

Publication 1757-UM006A-EN-P - May 2002
Integrating Fieldbus into Rockwell Automation Logix System 2-17
• Discrete process output from the FIM with backcalculation
feedback.
Bit types 5 and 6 described in Table 2.B support publish/subscribe
communications in Cascade mode or client/server communications in
Remote Cascade mode. And, the analog values can also be used in the
Remote Out mode.
Fieldbus also supports direct device-to-device (peer-to-peer)
publish/subscribe connections independent of the FIM. The FIM can
also monitor (subscribe to) the data published between the functions
blocks of these fieldbus devices.
Fieldbus status data details
According to Foundation Fieldbus specifications, every fieldbus
function block input and output connection must support a status byte
that provides the following status indications.
• Data Quality (usability)
• Bad Data Cause
• Degraded Data Cause
• Limit Conditions
• Cascade Control Initialization, Rejection
• Fault-State Initiation, Indication
• Local Override Indication
• Worst Case Alarm Indication
• Upstream Block Class Identification