End of Line Resistors The purpose of End Of Line ("EOL") Resistors for a security sensor is to allow the security system to be able to tell the difference between open and closed contacts (ie normal operation of the sensor) and open circuit and short circuit of the zone wiring (due to wiring faults or caused by someone cutting the wires).
EOL Resistor Values for Comfort The two resistor values used in Comfort are 2.2 K ohms (red/red/red colour code) in series with the contact and 4.7K (yellow/purple/red colour code) ohms in parallel with the contact. (in older systems, 2.7K was used instead of 2.2K for the series resistor). The EOL resistors are provided in the accessories pack together with the battery leads.
Effect of Double EOL Resistors
If Double End-Of-Line Resistors are connected and the Zone wires are cut or shorted together while the security system is NOT armed, a Zone trouble Alarm is reported for the zone, which will cause the keypad to beep fast for 10 seconds, and cause the keypad LCD to display the zone with the trouble condition. If the security system is armed and the zone trouble occurs, this will cause an immediate Intruder Alarm (as it could mean that someone has cut the alarm cable).
Comfort has an option whether to have NO EOL, or Double EOL by jumper selection on JZ1 to JZ8 headers.
Connections for No EOL Resistors are shown below. The zone shunt for each Zone JZ1, JZ2.. to JZ8 should be positioned on the 3 pin header so that it is closer to the Zone terminal block. The diagram shows 2 sensors in series. The Tamper connections are shown for PIRs and detectors. Tamper connections are usually not present for Magnetic door and window contacts.
If NO EOL is selected, Zone Trouble will not be detected. An open circuit and a short circuit on the wiring will be no different from an Open Contact or Closed Contact, and will trigger an alarm accordingly when the system is armed. Note that opening the Tamper connection has the same effect as cutting the zone wires.
Connections for Double EOL Resistors are shown below. The zone shunt for each Zone JZ1, JZ2.. to JZ8 should be positioned on the 3 pin header so that it is away from the Zone terminal block. The Tamper connections are shown for PIRs and detectors. Tamper connections are usually not present for Magnetic door and window contacts.
If Double End of Line Resistors are connected to a Zone/Input, a Zone Trouble Alarm will occur if the zone wires are cut (or disconnected) or shorted.The keypad will beep for 10 seconds and "Zone Trouble, (zone name)" will be shown on the Keypad LCD. The zone name or number will be shown on the LCD
If a zone trouble occurs when the security system is armed, it causes an Intruder Alarm.
If the zone shunts are set to No EOL (ie shunt is closer to the terminal block), zone trouble should NOT occur in normal conditions. However a Zone Trouble may occur if there is an external voltage on the zone input (not just open or short), OR the zone shunts may be having poor contact due to oxidation. remove the shunt and insert or replace with another new shunt
Last edited on Saturday Aug 4th, 2018 07:19 am by slychiu