The 1747-NP1 module is a power supply module for Allen-Bradley SLC 500 systems. The 1747-NP1 module is designed to be wall-mounted and its input voltage rating is 120 Volts AC. The 1747-NP1 module is one of the options available for providing power to the Allen-Bradley 1747-AIC link coupler which is used for DH-485 networks. Other options include the Allen-Bradley 1747-NP2 global desktop power supply or an external DC power supply rated for 190 milliamps and 24 Volts DC. The link coupler provides a connection for each SLC 500 node. The link coupler provides electrical isolation between peripheral connections and the processor, leading to 1500 Volts of electrical-optical isolation. The recommended cable for DH-485 communication is the Belden #3106A or the #9842 cable. The cable is shielded and jacketed with 1 drain wire and 2 twisted wire pairs. One wire pair provides a balanced signal line, and 1 wire from the other pair provides a common reference between nodes on the DH-485 network. The purpose of the shield is to protect against electrostatic noise.

The DH-485 communication cable on the 1747-NP1 module is comprised of a number of daisy-chained cable segments that reach a maximum length of 1219 meters. When the programmable controller is connected to the link coupler, the processor provides power to both the peripheral device and the link coupler. However, if the processor is not connected to the link coupler, then a 24 Volts DC power supply module such as the 1747-NP1 module can be used to power up the link coupler. The power requirement of the 1747-AIC link coupler is 85 milliamps at 24 Volts DC, which goes up to 190 milliamps if a peripheral device is also connected.