When programming Zones 2-8 on a Vista security panel you are required to define the Hardwire Type used for a particular zone. The hardwire type defines how the panel communicates with the sensor.
- 0 EOL - This is the most common hardwire type used. It defines that a 2K resistor is installed in series with the sensor circuit when using sensors that are closed in a normal state (open results in an alarm condition). For sensors which area opened in a normal state (closed or short trips an alarm) the resistor is wired in parallel to the sensor.
- 1 NC – A normally closed circuit has no resistor in the circuit. The sensor is closed in a normal state, an open circuit results in an alarm condition.
- 2 NO – A normally open circuit is the opposite of NC
- 3 Zone Doubling - Zone doubling allows for two sensors to be landed on one zone and yet the panel can identify if either or both of the zones is opened or closed. Zone doubling can only be used on Zones 2-8. A zone doubling resistor kit is provided with every new Vista 20P. The kit contains a 3K and 6.2K resistor. The 3K resistor is used for the sensors on zones 2-8 (if that zone is programmed as a Zone Double hardwire type) and the 6.3K resistor is used on the paired zone (10-16). A detailed diagram of zone doubling including on the door of every Vista 20P.
- 4 Double-Balanced – This hardwire type allows for two, series wired, sensors per zone with each sensor containing a 2K resistor. This hardwire type is rarely used.
End of Line Resistors (EOLR) used for hardwire type 0 , 3 and 4 should always be located at the sensor location in commercial installations. The EOLR provides circuit supervision should the wire be shorted between the panel and sensor. It is common practice by most security installation companies to install EOLR’s at the panel for residential installation even-though the zone could be programmed as an NC and not use an EOLR. So why?
The practice of installing resistors at the panel is to maintain programming continuity between commercial and residential installations as well has prevented installation errors when using zone expanders which only use EOL hardwire types. It is also good practice to write the zone number on the beanie at the panel.