Can I Use an External Alarm with the TV2
The TV2 is equipped with a N/O (normally open) dry-contact relay that can trigger an alarm, a buzzer, a bell, a light, an auto dialer, or other warning device. Since the relay is a dry-contact relay there is no power supplied when it closes, however an external alarm or light which has it's own power supply can be wired through the relay so it will activate when an alarm sounds.
The relay's 'trigger conditions' are set for each sensor on its alarm menu. The alarm must be 'enabled' for it to work properly. Each sensor has a high and a low set-point with delays. Setting the delay properly will ensure that no false alarms will be triggered. More information can be found on how the alarm works in the 'Alarm Behavior' note. Once an alarm is triggered the internal speaker will sound and the screen will blink showing the alarm conditions. The speaker can be silenced by pressing the 'Esc' key. In addition, if the TV2, is auto downloading to a computer either through the USB cable or the Wired Ethernet port a text or email message can be sent when an alarm occurs.
The cable between the TV2 and an auto dialer can be any length needed. It is simply a two conductor cable between the relay on the TV2 and the RJ11 connector which plugs into the auto dialer. Several TV2 can even share the wire, by wiring them in a star configuration. The relay is fused at 30vdc and 0.5amps.
Many of Two Dimensional Instrument's customers use an auto dialer to call their cell phone if an alarm is triggered'. We offer an several different auto dialers that will dial multiple different numbers (i.e. phone, pager, cell) and leave a message when triggered, although any auto dialer that can be triggered with a dry contact relay will work equally well.
The auto dialer pictured here has an external power supply and has its own battery backup. However the battery is only a four-hour battery. So in the event of a power failure you should ensure that the TV2 'power out' alarm is activated so you will receive a call as soon as power is interrupted. An emergency battery for the auto dialer is also available which will continue to operate the dialer for 24 hours if wall power is missing.