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selecting TIMR for A1FN or A2FN). The output 1 hysteresis (O1HY) is enabled in case of PB1
= 0. The heat only on-off control function is shown in the following diagram.
Figure 4-28.Heat Only ON-OFF Control
The ON-OFF control may introduce excessive process oscillation even if Hysteresis is
minimized to the smallest. If ON-OFF control is set (i.e. PB1 = 0), TI1, TD1, CYC1, OFST, CPB
and PL1 will be hidden and have no function to the system. The manual mode, auto-tuning, self-
tuning and bumpless transfer will be disabled too.
Select REVR for OUT1, set TI1 to 0, SP1 is used to adjust set point value, TIME is used to
adjust the dwell timer (enabled by selecting TIMR for A1FN or A2FN). OFST been enabled in case
of TI1 = 0 is used to adjust the control offset ( manual reset ). Adjust CYC1 according to
The output 1 type ( O1TY ).Generally, CYC1= 0.5 ~ 2 sec for SSRD and SSR, CYC1=10 ~ 20 sec
for relay output .CYC1 is ignored if linear output is selected for O1TY. If PB1 is not equal to 0.
OFST is measured by % with range 0 - 100.0 %. In the steady state ( i.e. process has been
stabilized ) if the process value is lower than the set point a definite value, say 5 C, while 20 C is
used for PB1, that is lower 25 %, then increase OFST 25 %, and vice versa. After adjusting OFST
value, the process value will be varied and eventually, coincide with set point.
Using the P control ( TI1 set to 0 ), the auto-tuning and self-tuning are disabled. Manual
reset ( adjust OFST ) is not practical because the load may change from time to time and often
need to adjust OFST repeatedly. The PID control can avoid this situation. Selecting REVR for
OUT1, SP1 is used to adjust set point value.
TIME is used to adjust the dwell timer ( enabled by selecting TIMR for A1FN or A2FN ).
PB1 and TI1 should not be zero. Adjust CYC1 according to the output 1 type ( O1TY ). Generally,
CYC1 = 0.5 ~ 2 sec for SSRD and SSR, CYC1 = 10 ~ 20 sec for relay output. CYC1 is ignored if
linear output is selected for O1TY.
In most cases the self-tuning can be used to substitute the auto-tuning. See If self-tuning
is not used ( select NONE for SELF ), then use auto-tuning for the new process, or set PB1, TI1
and TD1 with historical values. If the control result is still unsatisfactory, then use manual tuning to
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