FAQ: How to connect a Red-series Controller to a commercial gate operator using an isolation relay?

Connecting a Red-series Controller to a commercial gate operator (such as Liftmaster, Elite, Doorking, and others) is relatively straight-forward. 

Newer model gate-operators from major manufacturers share a similar control board, which has a dedicated, dry-contact input for access control systems. Below the 'Fire Dept.' connector are the 'Exit' connector terminals. These terminals are designed to allow an external device (such as an access control system) to send an 'Open' command to the gate operator. The image below shows these connector terminals, designated as 'EXIT' with a + and - for each terminal. Despite the polarity shown on the terminals, the connection to a PDK controller is not polarity sensitive.

Instructions:

For newer gate operators:

1. Connect the Normally Open (NO) terminal from a dry-contact relay on the PDK Controller to either terminal on the 'Exit' connector (or appropriate terminals on the Gate Operator).
2. Connect the Common (C) terminal from the same dry-contact relay on the PDK controller to the other terminal of the 'Exit' connector (or appropriate terminals on the Gate Operator).

For older gate operators:

For older gate operators, you will need to determine where to connect the access control system and if the the input on the gate operator is a wet- or dry-contact. A wet-contact has voltage between the input terminal connections, while a dry-contact does not.

• If the gate operator has a dry contact, you will need to follow the steps above for a newer gate operator. 
• If the gate operator has a wet contact, you will need to use an 'isolation relay' to keep the voltage from the gate operator from feeding back to the Red-series controller. 

1. Connect the Positive (+) of the isolation relay to the Positive (+) on the reader port. 
2. Connect the Negative (-) of the isolation relay to the Normally Open (NO) of the relay for the port.
3. Place the jumper (D in the image above) on BUS and -.
4. Connect the Common of the open terminal on the gate operator to the Common (C) on the isolation relay.
5. Connect the other leg of the open terminal (this can vary by gate operator) to the Normally Open (NO) of the isolation relay.