Watlow MINICHEF 2000 - Manual (Page 57)

D e f i n i t i o n s o f E r r o r s
5 6 ■ Wa t l o w M I N I C H E F 2 0 0 0 H a r d w a r e & S o f t w a r e S e t u p G u i d e
Definitions of Errors
This control has the ability to detect different error conditions.
The outputs of the control will be shut off when any error condition occurs. If a menu is
running, it will be canceled upon any error condition.
Only one error will be displayed at a time. The error with the highest priority will be
the one displayed. When displaying errors, an error message will alternate with the
normal display. Errors will only be displayed in the operational mode.
Errors [Err`1], [Err`2] and [Err`3] are latching, meaning that once they occur, the
only way to clear them is to cycle power. The remaining errors are self-clearing, mean-
ing when the error condition goes away, the error will disappear.
EPROM checksum error [Err`1]
An EPROM checksum error occurs on power up when the bytes in the EPROM do not
add up to 0. The EPROM is programmed at time of manufacture in such a way that all
valid bytes should add up to 0.
EEPROM checksum error [Err`2]
An EEPROM checksum error occurs on power up when the bytes in the EEPROM do
not add up to 0.
RAM error [Err`3]
A RAM error occurs on power up when a RAM test is executed and fails. The RAM test
writes certain values to the RAM memory locations and then reads them back. If the
value read is equal to the value written in all cases the RAM test passes, otherwise it
fails.
Calibration Error [Err`4]
A Calibration Error occurs when stored calibration values have been corrupted and may
make the controller temperature readings inaccurate.
A/D underflow error [Err`5] (channel 1), [Err`9] (channel 2)
An A/D underflow error occurs when the electrical signal from the sensor is outside of
the measurable range of the A/D circuit. This can be caused by incorrect sensor type,
reversed sensor leads, or measuring temperatures outside the sensor range.
A/D overflow error [Err`6] (channel 1), [Err10] (channel 2)
An A/D overflow error occurs when the electrical signal from the sensor is either miss-
ing or outside the measurable range of the A/D circuit. This can be caused by an open
sensor or measuring temperatures outside the sensor range.
Under range error [Err`7] (channel 1), [Err11] (channel 2)
The under range error occurs when the control is unable to accurately calculate the
temperature even though the A/D is able to measure the signal. This is caused by mea-
suring temperature below the temperature range of the control.