Instruction manual
Instruction manual  αlpha DO 2000 
23 
1.  Select the “CNTR” subfunction, then press the ENT key. 
2.  Selecting the controller type: press the ▲ or ▼ key to select the suitable controller type: 
−  OFF = controller off 
Use control Off to operate controller as a monitor only or to prevent relays from 
switching. 
−  L.CT = limit value control (on/off control). 
Use limit control with pumps or valves for fast response 
−  P/PI = proportional/integral control 
Use proportional control to operate your pumps smoothly or for precise control of 
proportioning valves. Use PI controller to eliminate steady state error. 
Note: please refer to Appendix 4 for detailed information on controller settings. 
Press the ENT key to confirm your selection. 
−  If the controller is set to limit value control (L.CT): 
3.  Selecting the relay status under Non-Alarm condition: press the ▲ or ▼ key to choose 
the desired relay status (de-energized = “DEEN” or energized = “EN”). Press the ENT key to 
confirm your selection. 
−  If the controller is set to proportional control (P/PI): 
4.  Selecting the proportional controller type: press the ▲ or ▼ key to select the suitable 
controller type (“PLC” = pulse length control, “PFC” = pulse frequency control). Press the ENT 
key to confirm your selection. 
−  If the proportional controller type is set to pulse length control (PLC): 
5.  Selecting the relay status under Non-Alarm condition: press the ▲ or ▼ key to choose 
the desired relay status (de-energized = “DEEN” or energized = “EN”). Press the ENT key to 
confirm your selection. 
6.  Setting the proportional range: Press the ▲ or ▼ key to set the proportional range (setting 
range: 10 to 500%). Press the ENT key to confirm your setting. 
7.  Setting the pulse length: Press the ▲ or ▼ key to set the pulse length (setting range: 0.5 to 
20 seconds). Press the ENT key to confirm your setting. 
8.  Setting the integral action time: Press the ▲ or ▼ key to set the integral action time 
(setting range: 0.0 to 999.9 minutes). Press the ENT key to confirm your setting. 










