Datalogic GWY-01-PBS-01, Reference Manual

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GATEWAY OVERVIEW
17
2
2.4.2 Total System Current Consumption
NOTE
The current consumption values of each product are given in the Technical
Features paragraph of the relative Installation manual and refer to the min
and max input voltage range. These values already include an adequate
safety margin. The consumption values given in the following examples have
been interpolated for an input voltage of 24 Vdc.
Max Gateway Current: 200 mA @ 12 Vdc (133 mA @ 24 Vdc).
Max Controller Current: 366 mA @ 24 Vdc for Cobalt HF-Series, 87 mA @ 24 Vdc for
C0405-Series, etc. (refer to controller’s spec).
Calculating Total System Current Consumption:
Total System Current Consumption = [Max Gateway C (Max Controller Current x
Number of Controllers)]
Example
A Subnet16™ network powered at 24 Vdc is composed of a GWY-01-PBS-01 connecting
eight C0405-485 RFID Controllers.
Total System Current Consumption = [0.133 A + (0.087 A X 8)] = 0.829 A
2.4.3 Cable Voltage Drop
In addition, each RFID controller on the Subnet will experience a certain amount of voltage
drop depending on the length of the cable.
Cable Resistance per Meter

ThinNet = 0.058 ohms per meter per wire

ThickNet = 0.0105 ohms per meter per wire
Calculating Voltage Drop
Voltage Drop = (Max Controller Current x Number of Controllers) x (Cable Resistance per
Meter per Wire
1
x Cable length in Meters)
Example
A Subnet16™ network is composed of a GWY-01-PBS-01 connecting eight C0405-485 RFID
Controllers (87 mA each @ 24 Vdc). A total of 20 meters of ThinNet cables are used to
connect the devices, which have Cable Resistance = 0.058 Ohms per meter per wire. The
network power is 24 Vdc.
2
Voltage Drop = [0.133 A GWY + (0.087 A x 8 controllers)] x [(0.058 x 2) x 20 meters] =
1.92 Vdc
24 Vdc - 1.92 = 22.08 Vdc at controller number 8
1
The resistance calculation must include both wires (Vdc and GND).
2
This example assumes the power supply is placed at the end of the network, therefore controller #8 is the worst case. By
placing the power supply in the middle of the network the voltage drop at the ends is reduced.