Mercury MR52 connections - Synergis Cloud Link

Synergis™ Cloud Link Hardware Installation Guide

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As part of your installation, you might need to include a Mercury MR52 interface module.

The following diagram demonstrates how to connect the module.
MR52-S3 unit with connections
A Reader connections The wire colors in the illustration refer to "pigtail" HID readers; the information in parentheses refers to "terminal block" HID readers.
B Inputs Inputs 1 to 8 can be configured to use End-Of-Line (EOL) resistors, and for normally open or normally closed contacts.
C Address switches Used to set the device address. For more information on address settings on the Mercury module, refer to the manufacturer's instructions.
D Reader power 12V = 12 V dc at readers, PT = voltage “passed through” to readers.
IMPORTANT: For UL294 compliant Synergis™ installations, always install the jumper in the PT position.
E 2W/4W Select Install jumper in 2W position (4W is not supported).
F Line termination For end-of-line interface modules, install jumper J5 (MR52) or J4 (MR52-S3) for 120 Ohm line termination (J6 is not used).
G RS-485 RS-485 bus connection to other Mercury modules.
H Relay outputs 6 x Form-C

MR52: 5A inductive @28 V dc, 0.6 PF

MR52-S3: NO: 5A, NC: 3A, inductive @28 V dc, 0.6 PF

I Power In Connect + to VIN (observe polarity). Connect - to GND. Use 20 AWG wires minimum.
J Resistors For OSDP integrations, prevent readers from misinterpreting noise on a non-driven RS-485 line as data by installing a 1k ohm pull-down resistor from D0 to GND on both Reader 1 and Reader 2.

For wiring distances over 10 meters, install a 120 ohm termination resistor between D0 and D1, as well as between A (-) and B (+) on the RS-485 bus of the last connected reader.

To find out whether you need to add a 1K ohm pull-down resistor between D0 and GND, see KBA-78953.