Reader Wiring - HID Mercury LP4502 Installations And Specifications

Powering
Trusted Identities

2.6 Reader wiring

Each reader port supports a reader with TTL (D1/D0, Clock/Data), F/2F (standard or supervised), or 2-wire
RS-485 signaling (OSDP reader for example). Power to the reader is selectable: 12 V DC (VIN must be greater
than 20 V DC), or power is passed-through (PASS) from the input voltage of the LP4502 (TB1-VIN) and is
current limited to 300 mA for each reader port. Readers that require different voltage or have high current
requirements should be powered separately. Refer to the reader manufacture specifications for cabling
requirements. In the 2-wire LED mode the Buzzer output is used to drive the second LED. Reader port
configuration is set via the host software. Do not terminate any RS-485 devices connected to a reader port.
To fully utilize each reader port:
TTL signaling requires a 6-conductor cable (18 AWG)
n
F/2F signaling requires a 4-conductor cable
n
RS-485 signaling requires two 2-conductor cables. Use one cable for power (18 AWG, 1-pair) and one
n
cable for communication (24 AWG, 1-pair, shielded)
Note: For OSDP cable lengths greater than 200 ft (61 m) or EMF interference, install 120Ω +/- 2Ω resistor
across RS-485 termination ends.
Note: Data 0 and Data 1 wires for Wiegand may be reused for OSDP. However, standard Wiegand cable may
not meet RS-485 twisted pair recommendations. The reuse of cable works best on shorter cable
lengths at lower data rates.
J7 – Reader power select
12V PASS Reader power
12 V DC is available on reader ports (VIN > 20 V DC)
VIN power is "passed through" to reader ports
Caution: Install jumper J7 in the 12V position ONLY if the input voltage (VIN) is greater than 20 V DC. Failure
to do so may damage the reader or LP4502.
Input power Reader power select
24 V DC Pass-through
24 V DC 12 V DC
12 V DC Pass-through
12 V DC 12 V DC
PLT-05246, A.4
Reader output
24 V DC
12 V DC
12 V DC
0 V DC
13
HID Mercury™ LP4502 Controller
Installation and Specifications
Notes
Caution: Do not use
June 2021