model 2704 controller installation and operation handbook - Soliton

Programmer Operation
2704 Controller
6.3. THE 2704 SETPOINT PROGRAMMER DEFINITIONS
6.3.1. Run
In run the programmer varies the setpoint in accordance with the profile set in the active
program.
6.3.2. Hold
In hold the programmer is frozen at its current point. In this state you can make temporary
changes to program parameters such as a target setpoint, ramp rates and dwells (if
programmer configured for ramp rate) or segment duration (if programmer configured as
Time to Target). Such changes will only remain effective until the end of the currently
running segment, when they will be overwritten by the stored program values.
6.3.3. Reset
In reset the programmer is inactive and the controller behaves as a standard controller, with
the setpoint determined by the raise/lower buttons.
6.3.4. Servo
When a program is run the setpoint can start from the initial controller setpoint or from the
current process value. Whichever it is the starting point is called the servo point. This can be
set in the program.
The usual method is to servo to the process value because this will produce a smooth and
bumpless start to the process.
If, however, when using a Ramp Rate programmer, it is essential to guarantee the time period
of the first segment it may be better to set the controller to servo to setpoint. (Note: in a
Time to Target programmer the segment duration will always be determined by the setting of
the Segment Duration parameter.)
6.3.5. Hot Start
Hot start can occur in any segment type, for any PSP but is most useful to ramp segments.
When run is initiated it allows the program to automatically advance to the correct point in
the profile which corresponds to the operating value of the process. Hot start is enabled in
configuration level and specifies which programmed variable to use when deciding the
correct segment.
6-4 Installation and Operation Handbook. Part No HA026502 Issue 1.0 Apr-00