Before adding OSDP readers to your Mercury controllers, read the following considerations.
Supported onboard OSDP readers with Mercury controllers
|Model||Onboard reader ports||Max onboard OSDP readers per panel|
|MR52-S21||2||2 (one per port)|
|MR52-S3||2||2 (one per port)|
|MR51e||2||2 (two on one port only)|
|MR62e||1||4 (four on one port)|
|EP1501||2||2 (two on one port only)|
|EP1502||2||2 (one per port)|
|EP4502||2||2 (one per port)|
|LP1501||2||2 (two on one port only)|
|LP1502||2||2 (one per port)|
|LP4502||2||2 (one per port)|
1 Series 2 MR50 and Series 2 MR52 do not support OSDP Secure Channel.
Wiring instructions for OSDP readers
- A 1K-ohm pull-down resistor must be added between the Mercury DAT/D0 and GND lines on interface modules and EP/LP controllers.
- The pull-down resistor must be installed on the panel.
- To function properly, there must not be any ground faults in the installation. Ensure that the DC Ground (power supply return) is not connected to earth ground.
- Wiring for Wiegand can be reused for OSDP. However, standard Wiegand cables might not meet RS-485 twisted pair recommendations.
- Star-shaped wiring is not recommended.
To find out whether you need to add the 1K ohm pull-down resistor, see KBA-78953.
For more information about how to wire the OSDP readers, see Connecting Mercury interface modules in Synergis™ Cloud Link” in the Synergis™ Cloud Link Hardware Installation Guide.
Termination resistorsThe following guidelines are especially important if you are working with high baud rate, for example, at 115,200 baud:
- For OSDP cables longer than 200 ft. (61m) or EMF interference, install a 120 ohm resistor on both ends of the RS-485 daisy chain.
- For Wiegand cables longer than 32 ft. (10m) or EMF interference, install a 120 ohm resistor on both ends of the RS-485 daisy chain.
If communication errors occur, you can lower the baud rate, add termination resistors, or both.