As part of your installation, you might need to include a Mercury MR50 interface module.
|A||Reader connections||Connect one reader.
NOTE: The wire colors in the illustration refer to "pigtail" HID readers; the information in parentheses refers to "terminal block" HID readers.
|B||RS-485||RS-485 bus connection to other Mercury modules.|
|C||Line termination||For modules at end of line, install jumper J4 (MR50) or J1 (MR50-S3) for 120 Ohm line termination.|
|D||Address jumpers / DIP switches||Used to set the device address. For more information on address settings on the Mercury module, refer to the manufacturer's instructions.|
|E||Power In||Connect + to VIN (observe polarity). Connect - to GND. Use 20 AWG wires minimum.|
|F||Tamper input||MR50: Normally closed switch (J3)
MR50-S3: Normally open switch (J2)
|H||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 TB4.
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 1k ohm pull-down resistor between D0 and GND, see KBA-78953.