User`s manual

5-12
<Toc> <5. Parameters>
IM 05D01D12-41E 6th Edition: Mar. 25, 2005-00
● Precautions for Use of Heater Burnout Alarm
(1) The heater burnout alarm can be used only in on-off control (relay output) or in time
proportional PID control (relay output, voltage pulse output). It cannot be used in continu-
ous PID control (current output). Only heating-side can be used in heating/cooling control.
(Cooling-side cannot be used.)
(2) Timing which detects an alarm is as follows.
- In time proportional PID control: When on-state time of control output is 130 ms or longer,
heater current value is detected and measured heater current value is updated. Heater
current value is detected 100 ms after control output turns on.
- In on-off control output: Heater burnout is detected in on state. (Heater burnout is not
detected in off state.)
- Heater burnout is not detected during Auto-tuning. However, if Auto-tuning is started
when heater burnout alarm occurs, alarm state will be held during Auto-tuning.
(3) In time proportional PID output, control output is updated for every cycle time. When
the controller is set to STOP state (preset output value POUT=0%), control output is actu-
ally turned off after the cycle time in progress elapses. When turning off heater in STOP
state, wait for one or more of cycle times after the operation is stopped.
Control
output
130ms
When turning off heater
in STOP state,
turn off here.
Heater burnout alarm may occur
if turning off heater here.
On
Cycle time (CT)
One or more of cycle times
75% 0%
Off
Control
output
value
RUN state STOP state
However, preset output value (POUT)=0%