Extech Instruments 48VTR User Manual page 20

Event Timer
The Event Timer starts counting when the control setpoint (SV) is reached and stops
counting after a programmed time value. Note that, unlike the Soak Timer, the Event Timer
does not switch the alarm relay ON when the timer starts. The alarm switches ON only after
the programmed time has elapsed.
1. Set the Alarm Function parameter 'A1Fu' to either an Event-ON or Event-OFF Timer.
On-timers start from an energized state and change to a de-energized state at the
switch points. Off-timers start from a de-energized state and change to an energized
state at the switch points. Refer to the Appendices for more information.
2. Select a timer value using the 'timE' parameter in the 1
3. The timer will begin counting when the PV reaches the SV but will not switch the
Alarm relay ON yet. The Alarm relay switches OFF only after the time elapses.
Event Timer Example
In this example, the 48VTR is controlling oven temperature. The process runs in 4-hour
cycles and an 'event' is scheduled two hours into the process. At the 2-hour point, the
Alarm relay activates a pump to allow a liquid into the oven.
1. Wire the Alarm relay in series with the AC power to the pump (as shown in the
diagram, above, for the Soak Timer example).
2. Set parameter 'A1Fu' (3
3. Set 'timE' in the 1
4. When the controller is powered the alarm relay will be OFF. When the PV reaches
SV, the relay remains OFF and the timer begins counting.
5. At the 2-hour mark the timer stops and the Alarm relay switches ON, allowing the
pump to add the liquid to the oven.
6. Note that the ON and OFF states, described in steps 4 and 5 above, can be reversed
depending on whether an ON Timer or an OFF timer is selected in the menu.
rd
Menu) to an Event-ON Timer (selection '8').
st
Menu to 120 minutes (2 hours).
st
20
Menu.
48VTR User Manual v6.0 10/1/20