Mr-dt – Keri Systems MR50 User Manual
Page 2
Mercury Security Corporation © 2014
MR50
DOC 10107-0009
REV 2.03
Page 2
Reader Wiring:
Door Strike Relay Wiring:
Two Form-C contact relays are provided for controlling door strike or other devices. The contact
ratings are 5 A for relay K1 and 1 A for relay K2. Load switching can cause abnormal contact wear
and premature contact failure. Switching of inductive loads (strike) also causes EMI (electromagnetic
interference) which may interfere with normal operation of other equipment. To minimize premature
contact failure and to increase system reliability, contact protection circuit must be used. The
following two circuits are recommended. Locate the protection circuit as close to the load as possible
(within 12 inches [30 cm]), as the effectiveness of the circuit will decrease if it is located far away.
ADDRESS 0
MR-DT
RS-485 MODE
9600 BAUD
READER PORT
2-WIRE RS-485
12Vdc (RED) (1)
TR+ (BLUE) (3)
TR- (GRAY) (4)
GROUND (BLACK) (2)
VO
TB4
GND
BZR
D0/DAT/T-
D1/CLK/T+
LED
RED (1)
GRN (2)
BLK (6)
ORG (5)
WHT (3)
BRN (4)
READER PORT
2-WIRE RS-485
GND
D0/DAT/T-
D1/CLK/T+
VO
LED
TB4
BZR
MR
-10/20
R
EA
DE
R
DATA1/DATA0 - CLOCK/DATA
2-WIRE RS-485
Diode Selection:
Diode current rating: 1x strike current
Diode breakdown voltage: 4x strike voltage
For 12 Vdc or 24 Vdc strike, diode 1N4002
(100V/1A) typical
MOV Selection:
Clamp voltage: 1.5x Vac RMS.
For 24 Vac strike, Panasonic:
ERZ-C07DK470 typical
TB3
K2
K1
C
NC
NO
C
NO
NC
K2
K1
TB3
K2
K1
C
NC
NO
C
NO
NC
K2
K1