User's Manual

Table Of Contents
MPR-2010-2.7E4-CN Page 8 7/22/2008
TABLE 3.4-1: Data Line’s Wiring Requirement
WIRE SIZE #22 AWG (0.6 mm Dia.) #24 AWG (0.5 mm Dia.)
WIEGAND (*) 500 ft (152 meters) 980 ft (300 meters)
RS-232 50 ft (15 meters) 50 ft (15 meters)
(*) LR-911 only
3.5 GROUNDING
Grounding is critical for proper operation of MPR-2010-2.7E45V-CN readers. When
installing the reader, it is crucial to assure that the earth ground is the best ground
available. If you elect to use the 120 VAC power ground, conduct a test by measuring
its resistance relative to a known good ground, such as a cold water pipe or structural
steel that is in direct contact with the ground. The resistance should be less than 50
ohms.
When using the GP I/O for sensing or display functions with a BN unit, make sure there
is no ground loop between the different sensors or displays.
For multiple LR-911 installations, it is critical that all units are connected to the same
grounding system. Using different grounding systems will create secondary current
paths or ground loops that can affect the performance and cause damage to LR-911.