User`s guide

Release E UMC800 Control Builder User’s Guide 259
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Appendix D – Controller Initialization
Introduction
Cold start execution
After any change from the Program to the Run mode, such as after a new configuration download, a Cold
Start is executed whereby:
• All function blocks are set to zero output
• All Variables are set to zero
• A previous selected set point profile is cleared
• A previous selected recipe is cleared
• All control loops will have their initial set point loaded to match the current PV.
All block entries and all values entered as Constants to external input pins of a block will be retained as
configured in Control Builder on download.
Initializing variables using a start-up recipe
Variables are used as inputs to certain blocks to allow an operator to change settings from the Operator
Interface using the Overview display listing, with variables assigned to this display format.
Typical usage is for biases, offsets as part of calculation blocks, alarm set points for Analog Alarm blocks,
timer remote presets for resettable timer blocks, inputs for the variety of Signal Selector blocks, etc. It is
not always desirable to have these initialize to zero on a configuration download.
To initialize these analog or digital variables to a desired value or state, a Recipe Selection Block can be
used [see Recipe Configuration (page 178)] for recipe setup procedures) in conjunction with a System
Monitor block as shown in Figure 73. The contents of this recipe (shown as number 1 but can be any
number up to 50), containing up to 50 values or statuses, is loaded after any configuration download. The
System Monitor block Newstart output delivers a pulse for one complete scan cycle after the download. A
latch is used to retain this status for 2 scan cycles to assure proper loading. Note the execution sequence of
the 3 blocks (latch is executed after recipe selection block).