User`s guide

Appendix B - Loop Application Examples
PID Control Algorithms
Release E UMC800 Control Builder User’s Guide 243
1/01
Example 7 - External selection of controller auto/manual mode
The MDSW (Mode Switch) Function Block is
used exclusively with the MDRQI (Mode Request
Input) of the PID or ON/OFF Function Block. Its
output provides encoded switch commands to the
PID Block
All inputs are OFF to ON edge-triggered, requiring
a separate input for each action. The example
shows digital inputs as the transfer inputs but any
digital status could be used.
Application: External mode switching of the
PID Block - changing a loop to MAN, to
AUTO, to LOCAL SP, or REMOTE SP.
Note: Mode switching is also provided as a
integral part of the Operator Panel, Loop
Displays
Use a single input to place a loop in manual
when the input is ON(1) and return to Auto
when OFF(0).
FAIL
Example 8 - Remote switching of control action and tuning constants
Loop Switch Function block
Function: Digital interface to initiate:
• Autotuning
• Change Control Action: Direct/Reverse Action
• Force Bumpless Transfer (rebalance the
algorithm)
• Select Tuning Set #1
• Select Tuning Set #2
FAIL