Check Points and Tip
6
p.8
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Recommended cable type and permissible length of cable
Description
Cable Specification
Maximum
Distance
Reader (Power and Data)
Reader -> ACU
Belden #9512, 22 AWG
4 conductor, shielded
150m
Belden #9514, 22 AWG
8 conductor, shielded
* Need thicker wire if you connect the reader with high current consumption.
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Reader connection
If you install the reader in a long distance between the ACU and the reader, you have to
remind that there will be a voltage drop between both ends of GND wire. For example, i
f you connect a reader with 100mA current consumption at 100m distance (assume to
using DC resistance of cable of 100Ω/100m) and the reader power is supplied from the
ACU, the voltage drop of the GND wire will be 1V. In this case, the Wiegand data signal
cannot be measured lower than 1V.
The most of ACU is capturing the signal by the voltage level of data input and 1V is the
critical point whether the ACU read the data logic “1” or logic “0” therefore the reader o
utput cannot be read correctly from the ACU.
You have to think about how you reduce the voltage drop between both ends of GND
wire. There will be two methods to reduce the voltage drop and ACU can read data corr
ectly.
○
Reduce the DC resistance of GND wire; Using thick cable or add more wires to GND
wire in parallel. If you connect 4 wires in parallel for GND, the DC resistance of GND
