307
Appendix
Troubleshooting
Checking Problems
If the Digital Controller is not operating normally, check the following points before requesting repairs. If the
problem persists, contact your OMRON representative for details on returning the product.
Timing Status Meaning Countermeasures Page
Turning ON the
power for the
first time
Temperature unit
(°C/°F) is flashing.
ST (self-tuning) is in
progress (default
setting: ON).
This is not a product fault. The temperature
unit (°C/°F) flashes while ST (self-tuning) is
being performed
62
Temperature error is
large.
Input error (S.Err dis-
play)
Input type mismatch Check the sensor type and reset the input
type correctly.
49
Thermometer is not
installed properly.
Check the thermometer installation location
and polarity and install correctly.
28
Communications are
not possible.
Non-recommended
adapter is being
used.
Make sure that the connected device is not
faulty.
Section 1 of
Communi-
cations
Manual
During opera-
tion
Overshooting
Undershooting
Hunting
ON/OFF control is
enabled
Select PID control and execute either ST
(self-tuning) or AT (auto-tuning).
When using self-tuning, turn ON the power
supply to the Digital Controller and load
(heater, etc.) at the same time, or turn ON
the load power supply first. Accurate self-
tuning and optimum control will not be pos-
sible if the power supply to the load is
turned ON after turning ON the power sup-
ply to the Digital Controller.
60
Control cycle is
longer compared
with the speed of
rise and fall in tem-
perature
Shorten the control cycle. A shorter control
cycle improves control performance, but a
cycle of 20 ms minimum is recommended in
consideration of the service life of the
relays.
52
Unsuitable PID con-
stant
Set appropriate PID constants using either
of the following methods.
• Execute AT (autotuning).
• Set PID constants individually using man-
ual settings.
60
HS alarm operation
fault
Use breeder resistance if the problem is
due to leakage current. Also investigate the
errors detected by the HS alarm function.
71
Temperature is not
rising
Specified operation
is unsuitable for
required control
(default: Reverse
operation)
Select either forward or reverse operation
depending on the required control. Reverse
operation is used for heating operations.
52
Heater is burnt out or
deteriorated.
Check whether heater burnout or deteriora-
tion have occurred. Also investigate the
errors detected by the heater burnout
alarm.
71
Insufficient heater
capacity
Check whether the heater’s heating capac-
ity is sufficient.
---
Cooling system in
operation.
Check whether a cooling system is operat-
ing.
---
Peripheral devices
have heat preven-
tion device operat-
ing.
Set the heating prevention temperature set-
ting to a value higher than the set tempera-
ture of the Digital Controller.
---
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