Control Modes; Mode Definitions; Table 4-5 Control Mode Definitions - Honeywell UDC3500 Product Manual

4.7 Control Modes

ATTENTION
After changing a Local Setpoint value, if no other key is pressed, it then takes a minimum of thirty (30)
seconds elapsed time before the new value is stored in non-volatile memory. If controller power is
removed before this time, the new setpoint value is lost and the previous setpoint value is used at
power-up. If, after changing the LSP value, another key is pressed, then the value is stored
immediately.

4.7.1 Mode Definitions

Control Mode
AUTOMATIC with In automatic local mode, the controller operates from the local setpoints and
automatically adjusts the output to maintain the PV at the desired value.
LOCAL
In this mode you can adjust the setpoint.
SETPOINT
See Subsection 4.8 – Setpoints.
In automatic remote mode, the controller operates from the setpoint measured at the
AUTOMATIC with
REMOTE remote setpoint input. Adjustments are available to ratio this input and add a
constant bias before it is applied to the control equation.
SETPOINT
See Subsection 3.12 Input 1 or 3.14 Input 2.
MANUAL In the manual mode, the operator directly controls the controller output level. The
process variable and the percent output are displayed. The configured High and
Low Output Limits are disregarded and the operator can change the output value,
using the increment and decrement keys, to the limits allowed by the output type
(0 % to 100 % for a time proportioning output or –5 % to 105 % for a current output).
In the manual cascade mode, both control loops are in manual although there is still only one
MANUAL
output active. This mode is used to bring both loops into a reasonable operation area, at
CASCADE
which point the unit is placed into the automatic cascade mode.
If Loop 1 is placed in Manual control mode, then Loop 2, if in auto, is then placed in a pseudo-
manual mode thereby eliminating output bumps when Loop 1 is returned to Automatic control
mode.
In Automatic cascade mode, there are two control loops, with one loop's output acting as the
AUTOMATIC
setpoint for the second control loop. There is only one physical output in this mode.
CASCADE
10/05

Table 4-5 Control Mode Definitions

UDC3500 Universal Digital Controller Product Manual
Monitoring and Operating the Controller
Definition
189