When installing NO door contacts, where should the EOL resistor be placed?

When installing door contacts, it's essential to understand the role of the End of Line (EOL) resistor in ensuring the system functions correctly. The End of Line resistor is used in alarm systems to monitor the integrity of the wiring.

Placing the EOL resistor in parallel at the device level, rather than in series or at other points, provides critical benefits. It allows the system to detect whether the contacts are open or closed by monitoring the resistance across the wiring. If the door contacts are tampered with, the change in resistance will trigger the alarm system.

Positioning the resistor at the device level also minimizes the possibility of false alarms due to wiring issues, such as breaks or shorts occurring further down the line. This setup ensures that any interruption specifically related to the door contacts will be effectively monitored.

By utilizing this configuration, maintaining system reliability and security becomes more efficient, as the control panel can precisely interpret whether the door is secure or if an alarm condition exists. This importance makes the choice of placing the EOL resistor in parallel at the device the best practice in this scenario.