Specifications
Installation
9
NXA-PDU-1508-8 Power Distribution Unit
AxLink Wiring Guidelines
AxLink devices require 12 VDC power to operate properly. The necessary power is supplied via the AxLink
cable. The maximum AxLink wiring distance is determined by power consumption, supplied voltage, and the
wire gauge used for the cable.
Use the 3-step formula below to calculate the maximum wiring lengths allowable between the PDU and
connected AxLink devices.
1. <Total current consumption of all connected AxLink devices> x <Resistance/Foot> x 2 =
<voltage drop per foot> (see table below for Resistance/Foot values.)
2. <Power supply voltage> - 12 VDC = <surplus voltage dissipation for cable run>.
3. <surplus voltage dissipation for cable run> / <voltage drop per foot> = Max. distance.
The following table lists the resistance factors used in the formula.
CONFIG DIP Switch
The NXA-PDU-1508-8 uses an 8-position DIP Switch (labelled “CONFIG”) to specify a unique device
address for itself in a NetLinx Control System (FIG. 10).
Setting the Device Address of the PDU
The NXA-PDU-1508-8 firmware implements 8 AxLink device IDs, starting from the device ID denoted by the
DIP switch. The device IDs used by the NXA-PDU-1508-8 are as follows:
Dev 1: (Power Outlet 1) + (AxLink-Bank 1 Power) + (Input Voltage) + (Temp)
Dev 2: (Power Outlet 2) + (AxLink-Bank 2 Power)
Dev 3-8: (Power Outlets 3-8)
To set the Device Address:
1. If connected, disconnect the power supply.
2. Set the CONFIG DIP switch according to the values shown below:
The device number is set by the total value of DIP switch positions that are in the ON position. Note that the
ON position is indicated on the DIP Switch.
If you later change the device number, remove and reconnect the power connector to enter the new device
number into memory.
Cable Gauge/Resistance Factors
Solid Copper Wiring Stranded Copper Wiring
Wire gauge Resistance/Foot Resistance/Foot
18 AWG .00639 .00692
20 AWG .0101 .01090
22 AWG .0162 .01690
24 AWG .0257 .02770
FIG. 10
CONFIG DIP Switch
12345678
AxLink devices IDs are always in the range of 1-255. However, the PDU requires
seven open device numbers above the PDU device number setting to accommodate
its sub-devices. Therefore, device addresses 249-255 are not valid for the PDU.
Switch 12345678
Value 1 2 4 8 16 32 64 128
Use the "Dip Switch2" software application to calculate dip switch position values
(available to download from www.amx.com).