Thermcraft XST-6-0-36-3V - Manual (Page 81)

Installation and Operation Handbook Tuning
2408 and 2404 Controller 4-7
MOTORISED VALVE CONTROL
The 2408 and 2404 can be configured for motorised valve control as an alternative to the
standard PID control algorithm. This algorithm is designed specifically for positioning
motorised valves.
These are ordered pre-configured as Model numbers:
• 2408/VC and 2404/VC motorised valve controllers
• 2408/VP and 2404/VP motorised valve controllers with a single setpoint programmer
• 2408/V4 and 2404/V4 motorised valve controllers storing four setpoint programs.
• 2408/VM and 2404/VM motorised valve controllers storing twenty setpoint programs.
Figure 1-11 in Chapter 1 shows how to connect a motorised valve controller. The control is
performed by delivering open, or close, pulses in response to the control demand signal.
The motorised valve algorithm can operate in one of three ways:
1. The so-called boundless mode, which does not require a position feedback potentiometer
for control purposes; although one can be connected and used purely to display the
valve’s position.
2. Bounded, (or position), control mode, which requires a feedback potentiometer. This is
closed-loop control determined by the valve’s position.
The desired control mode is selected in the ‘ inst’ list in configuration level.
The following parameter list will appear in the navigation diagram shown in Chapter 2, if
your controller is configured for motorised valve control.
Name Description Values
mtr Motor list Min Max Default
tm Valve travel time in seconds.
This is the time taken for the valve to travel from
its fully closed position to its fully open position. 0.1 240.0 30.0
In.t Valve inertia time in seconds.
This is the time taken for the valve to stop moving
after the output pulse is switched off. OFF 20.0 OFF
bAc.t Valve backlash time in seconds.
This is the minimum on-time required to reverse
the direction of the valve. i.e. the time to
overcome the mechanical backlash. OFF 20.0 OFF
mp.t Output pulse minimum on-time, in seconds. Auto 100.0 Auto
U.br Valve sensor break strategy. rESt, uP, dwn rESt
Table 4-3 Motorised valve parameter list