Setting up Multi-Drop for Multiple OSDP Readers per Door

Larry Wile Updated by Larry Wile

Setting up Multi-Drop for Multiple OSDP Readers per Door

Introduction

Mercury LP controllers support the ability to assign more than one reader to a given door node over OSDP. This is done through creating a RS-485 bus. The limit per board is 4. The maximum number of readers that can be assigned to a single node is 3, by using Brivo’s Anti-Passback setting. 

Having more than one reader available reduces the number of door nodes for situations where two readers at one door are required. Examples of this are having a separate reader on a pedestal for ADA compliance, or at a vehicle gate where two different heights are needed for the size of vehicle. Another use is Anti-Passback. 

In this guide we will first walk through the different connection scenarios. We will then walk through the door setup for the primary and alternate readers. Finally we will walk through setting up Anti-Passback with Multi-Drop readers. 

Multi-Drop Scenarios

Multi-drop can be configured as follows:

Configuration A:

In this configuration, you are using both readers as inbound, or INGRESS readers. The system will not distinguish between the two readers. The readers must be addressed before connecting to the panel. The procedure for addressing the reader differs by manufacturer. For Brivo Smart Readers, please refer to the Reader Installation Guide. 

Configuration B:

In this configuration, you are using the readers for inbound and outbound traffic. You can use this configuration with or without Anti-Passback. Today, this configuration will report as the same door and will not report In or Out unless you are using Anti-Passback. Any time that you are using readers back to back on opposite sides of a wall, it is best to offset the reader placement by a minimum of 4-6” horizontally to ensure the readers do not interfere with each other. In the cases of mullion mounts to metal frames, less interference is possible. 

Configuration C:

In this configuration, you are using Anti-Passback to allow the alternate reader on another node to control the outbound access to the door. The primary and alternate readers are paired as inbound and the alternate reader on the other node is configured as an egress reader in ANti-Passback. Note that the use of this scenario will result in an Anti-Passback condition. One way to avoid this, if Anti-Passback is not required, is to set each group to “Immune to Anti-Passback”. Another solution would be to set a short (1 min.) reset interval for Anti-Passback. Any time that you are using readers back to back on opposite sides of a wall, it is best to offset the reader placement by a minimum of 4-6” horizontally to ensure the readers do not interfere with each other. In the cases of mullion mounts to metal frames, less interference is possible. 

NOTE: Follow all RS-485 termination instructions for properly setting up more than one OSDP per node.

NOTE: Some readers may require external power. 

Configuring Multi-Drop

In order to configure Multi-drop onto your panel, either select a door that you have already configured or create a new door. 

You will need to set the addresses

The alternate reader will automatically be reported as the door it is configured to unless the reader is assigned as the alternate reader for another Door in the AntiPassback Settings. 

Configuring Anti-Passback with Multi-Drop readers

To configure a reader as an Egress reader for Anti-Passback, you will want to configure the reader in the Control Panel page.

Using the scenarios described above, you can either use the same node’s alternate reader or another node’s alternate reader as the Egress reader. 

Setting the Alternate Reader as EGRESS

If you need to reverse the setup, where the primary reader is Egress, Select Egress for the primary reader. Then, when you assign your alternate reader it will automatically be assigned Ingress.

If you are using Configuration Scenario C above, you will Select Alternate Reader 2 rather than Alternate Reader 1 to act as your Egress reader.

How did we do?

Mercury Integration Capability Matrix

Brivo Mercury Solutions FAQs

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