5 Advanced Operations
5 - 18
E5@C Digital Temperature Controllers User’s Manual (H174)
Operation at Startup
If the SP ramp function is enabled when the Digital Controller is turned ON or when switching from
STOP to RUN mode, the process value reaches the set point using the SP ramp function in the
same way as when the set point is changed. In this case, operation is carried out with the process
value treated as the set point before the change was made. The direction of the SP ramp changes
according to the relationship between the process value and the set point.
Restrictions during SP Ramp Operation
• Execution of auto-tuning starts after the end of the SP ramp.
• When control is stopped or an error occurs, the SP ramp function is disabled.
Alarms during SP Ramp Operation
The operation of alarms during SP ramp operation depends on whether alarms are set to be based
on the ramp set point or the target set point (refer to the following diagrams). The set point to be
used is set in the Alarm SP Selection parameter.
PV<SP PV>SP
Alarm SP Selection = Ramp SP (Alarm Type: 1 (Upper/Lower Limits))
Alarm SP Selection = Target SP (Alarm Type: 1 (Upper/Lower Limits))
SP
PV
Rising
SP ramp
Set point
Power ON
Time
SP
PV
Falling
Time
Power ON
SP ramp
Set point
Temperature
Time
Alarm output ON
Alarm output ON
Temperature
Time
Alarm output ON
Alarm output ON
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