Honeywell Series A - About modes of operation

10. Appendix A
10.2. Standard Function Blocks
384 Experion PKS Series A Fieldbus Interface Module User's Guide R400
Honeywell July 2010
Fieldbus
AI Block
PID Block
AO Block
Device 1
Device 2
Figure 38 Using Function Blocks in fieldbus devices to form a control
loop.
About modes of operation
Every
Function block includes a mode parameter with configured permitted modes. This
structured parameter is composed of the actual mode, the target mode, the permitted
mode, and the normal mode. The normal mode is the desired operating mode. The actual
mode reflects the mode used during block execution. The target mode may be set and
monitored through the mode parameter. The permitted mode defines the allowable target
mode settings. The following table provides a summary of the available modes of
operation and their effect on operation.
Mode Abbreviation Operation Effect
Out of Service OOS
The block is not being evaluated. The output
is maintained at the last value, an assigned
fault state value -last value or configured
fault state value. Set Point is maintained at
last value.
Initialization Manual IMan
The block output is being set in response to
the back-calculation input parameter status.