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Pattern
Meaning
Three flashes, each of
increasing length
In manufacturing mode. This should not occur during normal operation.
Alternating low
brightness and high
brightness
Analog to Digital Converter failure. This is easily caused by low supply voltage,
but could also indicate hardware failure. Ensure supply voltage is within
specification and cycle power.
Brief high brightness
flashes
An out of bounds error has occurred due to the Heater Shutdown limits. This can
also occur if the maximum current rating is exceeded.
Fade On/Fade Off
Heater resistance/temperature is within Process Value Range limits, and no errors
are active. Available only in LED Mode 4.
On solid or semi-random
flashes of low brightness
Power is applied to heater. Available only in LED Modes 2 and 3.
Off
No power applied, Heater Output is de-energized, or LED in Mode 1.
Table 1
Frequently Asked Questions (FAQ)
Q:
How long will the CT398 maintain configuration in non-volatile memory?
A:
The specification states the retention is at least 20 years and will withstand at least 1 million writes.
Q:
Why isn’t the measured temperature of the heater surface the same as what is reported in the utility program?
A:
The CT398 uses the resistance of the heater’s element to determine the heater’s temperature. It is not uncommon for this
measured value to be higher than the heater’s surface temperature. External characterization of the setup is often required to
correlate heater element and heatsink temperature.
Q:
Why does the temperature slowly increase despite already exceeding the Setpoint?
A:
Try increasing the Pulse Rate period. In order to measure the heater’s resistance, power is briefly supplied to the heater
and the current and voltage are measured. If the CT398 checks too frequently and the heater / heat sink is relatively small,
this will result in excessive heating.
Q:
Can any heater be used with the CT398?
A:
Provided the applied voltage and heater resistance does not exceed the CT398’s output current rating, yes any heater may
be used as long as it uses a high TCR element. If a high TCR element is not used, the heater’s resistance may not change
enough relative to temperature to be useful.
