TE Technology TC-720 - Manual (Page 56)

ALARM LATCHES:
Alarm latches, when enabled, hold the alarm transistor signals and power output state as if they were in an alarm
condition, even if the temperature conditions that caused the alarm are no longer present. Alarm latches can be cleared by
clicking the “CLEAR LATCHES” OK button in the GUI, by pressing the “up arrow” for 3 seconds (TC-720 only), or by de-
energizing and reenergizing the temperature controller.
1. NO LATCHES: if an alarm condition clears itself, the alarm will automatically reset.
2. ALARM 1 LATCH: if an alarm is triggered from the control sensor, the software will continue to signal an alarm
condition until the condition is cleared and the “CLEAR LATCHES” OK button is clicked, or the latches are otherwise
cleared using the keypad (TC-720 only).
3. ALARM 2 LATCH: if an alarm is triggered based on the secondary sensor, the software will continue to signal an
alarm condition until the condition is cleared and the “CLEAR LATCHES” OK button is clicked, or the latches are
otherwise cleared using the keypad (TC-720 only).
4. ALARM 1&2 LATCH: if an alarm is triggered from either the control or the secondary sensor, the software will
continue to signal an alarm condition until the condition is cleared and the “CLEAR LATCHES” OK button is clicked,
or the latches are otherwise cleared using the keypad (TC-720 only).
INTERLOCK: when ENABLED, the INTERLOCK terminal (JP2-6) must be shorted to the controller circuit ground (LOGIC
SUPPLY JP2-7 or POWER GROUND JP7-3) in order to enable the main output of the controller. If the JP2-6 is not shorted to
circuit ground (i.e., it is open circuit) then the main output of the controller is disabled.
The interlock latch can be cleared by clicking the “CLEAR LATCHES” OK button in the GUI, by pressing the “menu key” + “up
arrow” for 3 seconds (TC-720 only), or by de-energizing and reenergizing the temperature controller.
1. DISABLED: whether the INTERLOCK terminal is shorted to ground or is open circuit it will have no effect on the
main output of the controller.
2. ENABLED WITHOUT LATCHES: Main output will be disabled if the INTERLOCK terminal is not shorted to ground,
and the main output will automatically be enabled again once the INTERLOCK terminal is shorted to ground.
3. ENABLED WITH LATCHES: Main output will be disabled if the INTERLOCK terminal is not shorted to ground, and
will only be enabled once INTERLOCK terminal is shorted to ground and the “CLEAR LATCHES” OK button is clicked,
or the latches are otherwise cleared using the keypad (TC-720 only).
• The Interlock is typically used as a safety feature with an external switch or thermostat.
• The controller has an internal 2.5 KΩ pull-up resistor connected to JP2-6, see Controller Schematic.
• When the interlock has disabled the output, the LCD screen on the TC-720 (non-OEM version) will flash “ILOPEN”
(for InterLock OPEN).
• Do not short INTERLOCK to controller chassis safety ground.
HIGH ALARM 1 SETTING: This sets the temperature at which an alarm will occur if the control sensor temperature exceeds
the set value. Only integer values are accepted. The set value must be greater than the value set in the LOW ALARM 1
SETTING, but less than 201 °C. If the set value is set to greater than 200 °C, no alarm will be signaled for any over-
temperature condition, essentially turning off the high alarm setting. “Inf” will be displayed if the high alarm setting is
turned off.
LOW ALARM 1 SETTING: This sets the temperature at which an alarm will occur if the control sensor temperature becomes
less than the set value. Only integer values are accepted. The set value must be less than the HIGH ALARM 1 SETTING but
greater than -41 °C. If the set value is less than -40 °C, no alarm will be signaled for any under-temperature condition,
essentially turning off the low alarm setting. “-Inf” will be displayed if the low alarm setting is turned off.
ALARM 1 DEADBAND: this defines a temperature difference above or below the LOW ALARM 1 SETTING or HIGH ALARM 1
SETTING at which the alarm status can be cleared (either automatically or manually depending on latch settings). For
example, if the HIGH ALARM 1 SETTING is set for 70 °C and the ALARM 1 DEADBAND is set for 10 °C, and an alarm condition
occurs, the control sensor would have to cool to 60 °C before the alarm could be reset.
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