Future Design MCT-MC 4.3, User Manual

Page: 34 / 186

MCT-MC
4.3
FDC MCT-MC - 34 - Configuring the MCT-MC
4.3.28 Alarm (1-3) Hysteresis
The alarm hysteresis can be set when the alarm function is set for a process or deviation type of alarm. It is
used to eliminate rapid on/off cycling of the alarm output by applying a safe-sided dead band to the alarm.
When the alarm set point is exceeded, the alarm will activate. The alarm will not deactivate until the process
rises above (for low alarm) or falls below (for high alarm) the alarm set point by the hysteresis value.
The hysteresis can be set from a minimum of 0.1 to a maximum of 50.0 for units of degrees Centigrade and to
a maximum of 90.0 for units of degrees Fahrenheit and linear input types.
4.3.29 Setpoint at Start of Automatic Program
The Setpoint at Start of Automatic Program entry is used to select the set point that will be used by the loop
control at the start of a ramp/soak program. The start set point selections are mutually exclusive, i.e., selecting
one will turn off the other. Once the desired starting set point has been selected, press the “Done” button to
return to the main Loop Configuration screen.
NOTE: If the MC control type is set for Dual Loop, Dual Loop + Cascade or Triple loop operation, it is
recommended that both loop 1 and loop 2 be set to the same selection so that both loop controls
start an automatic ramp/soak program in the same manner to avoid operator confusion.
The P41 and B42 loop control board provide a selection for using the start set point value of a
program. This selection is not supported by the MC and cannot be configured or entered for an
automatic program in the MC runtime application. Only the current PV or control SP selections are
supported.
The
Current process value selection will cause the loop control to immediately assume the current process
value as the set point when the program is started. If the program is started on a ramp step, the program will
begin ramping the set point from the current process value to the target set point of the step. If the program is
started on a soak step, the program will hold the set point at the process value for the duration of the soak step.
The
Current control setpoint selection will cause the loop control to use the current static set point when the
program is started. If the program is started on a ramp step, the program will begin ramping from the static set
point to the target set point of the step. If the program is started on a soak step, the program will hold the static
set point for the duration of the soak step.