Operating Characteristics; Introduction; Overview; Power Down / Power Up - Honeywell 900U02-0100 User And Installation Manual

8.1.

Introduction

This section applies to all controllers, that is, non-redundant and redundant. For operating characteristics
that unique to redundant controllers, see Redundant Operating Characteristics on page 173.
This section provides insights into system functioning that are useful in configuration, in installation
/commissioning tasks, and in normal and abnormal operation. For related information regarding
diagnostic indications, how they should be interpreted, and determining appropriate actions, refer to the
Diagnostics section in this user manual.
8.2.

Overview

The ControlEdge HC900 Controller components begin operation as soon as power is applied, and
continue until power is removed. The operation of the system varies according to the following
interacting factors:

Power transitions: Power DOWN / Power UP
Power DOWN transitions are usually planned and controlled, but in some cases, such as power
outages, are unintended. To ensure proper operation in either case, the ControlEdge HC900
Controller includes software that controls operation at power restoration. The controller handles a
Power-UP transition as one of two types: Cold Start or Warm Start

Operating Modes: Program (Locked), Program, Offline, Run, and Run (Locked)
Operating Modes are selected:
 by positioning the (Operating) Mode switch on the Controller Module or RSM,
 by selecting parameters on displays (Control Station, Designer Software).
 In some cases, mode transitions also restart (Cold Start or Warm Start) controller operation.

Results of diagnostics: in case of system hardware or software fault, the controller automatically
alters operation as appropriate for the diagnosed conditions.
8.3.

Power Down / Power Up

The ControlEdge HC900 Controller is designed to facilitate restoration of process operation after a power
outage. The active control configuration is maintained in battery-backed RAM, and the last configuration
update performed in the program mode is also stored in Flash memory on the Controller Module. When
power is restored, the system automatically enters a diagnostic procedure that checks the integrity of
hardware, software, and the control database. Depending on the results of the diagnostic, the controller
will execute either a Warm Start or a Cold Start.
Revision 10 ControlEdge HC900 Process & Safety Controller User and Installation Manual
May 2019

8. Operating Characteristics

165