Operating Two Loops Of Control - Honeywell UDC3500 Product Manual

4.20 Operating Two Loops of Control

Introduction
Operation of two individual loops of control is identical to operating a single loop of
control except that TUNING 2 group applies to Loop 2 only and four PID sets, 5 through
8, are available. TUNING group applies to Loop 1 with PID sets 1 through 4 applicable.
Operating modes and setpoint source
The rules for Auto/Manual modes and changing setpoint sources are the same as single
loop operation.
Keyboard operation
Note that the loop being displayed is the only loop affected by normal keyboard
operation. However, either loop can be reconfigured when in the Set Up mode regardless
of which is being displayed during normal operation.
Accutune III
Two independent loops or cascaded loops can be tuned at the same time, if so configured.
Setpoint Ramp or SP Programming
Either loop or both loops can be configured for a single setpoint ramp operation by
enabling the desired loop or loops (see Section 3 – Configuration)
An "H" or "R" will appear in the upper display when applicable, depending upon which
loop is being displayed.
Digital Inputs (remote mode switching)
Digital Input 1 is dedicated to Loop 1 when two loops or Cascade control is configured.
The other digital inputs may be configured to work on either loop.
Output Override Hi/Lo select
Output Override allows you to select the higher of Output 1 and Output 2 (Hi Select) or
the lower of Output 1 and Output 2 (Lo Select) to appear at Output 1 terminals to drive
the final control element. Refer to Section 5.12 for Override rules and block diagram.
Override prompts appear under the Algorithm Set Up group, function prompt OUT
OVRD.
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