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2.3
Control Output
There are 4 kinds of control modes can be configured as shown below.
2.3.1
Heat Only ON-OFF Control – (Used for Solonoids and Valves)
Select REVR for OUT1, Set PB to 0. O1HY is used to adjust the hysteresis for ON-OFF
control. The output 1 hysteresis (O1HY) setting is only available when PB = 0. The heat only ON-OFF
control function is shown below.
2-1.Heat Only ON-OFF Control
ON-OFF control may cause excessive process oscillations even if the hysteresis is set to the smallest value.
If ON-OFF control is used (i.e. PB = 0), TI, TD, CYC1, OFST, CYC2, CPB, DB will no longer be applicable
and will be hidden. Auto-Tuning mode and Bumpless transfer are not possible in on/off mode.
2.3.2
Heat only P or PD Control – (Used for Electric Heaters)
Select REVR for OUT1, set TI = 0, OFST is used to adjust the control offset (manual reset). If PB ≠0 then
O1HY will be hidden.
OFST Function: OFST is measured in % with a range of 0 - 100.0 %. When the process is stable, let’s say
the process value is lower than the set point by 5°F. Let’s also say that 20.0 is used for the PB setting. In
this example, 5°F is 25% of the proportional band (PB).
By increasing the OFST value by 25%, the control output will adjust itself, and the process value will
eventually coincide with the set point.
When using Proportional (P) control (TI = 0), Auto-Tuning will be unavailable. Refer to the “manual tuning"
section for the adjustment of PB and TD. Manual reset (OFST) is usually not practical because the load may
change from time to time; meaning the OFST setting would need to be constantly adjusted. PID control can
avoid this problem.
