NXT-MSC 2D/4D Controller Specifications

1.0 NXT-2D/-4D Dimensions

1. NXT Enclosure - 13.00 inches high by 10.5 inches wide by 3.00 inches deep
   - 33.02 cm by 26.67 cm by 7.62 cm.
   
   
2. NXT Controller PCB - 6.50 inches high by 5.50 inches wide by 1.00 inches deep, not including wiring connectors
   - 16.51 cm by 13.97 cm by 2.54 cm.
   
   

2.0 Power Requirements

1. 10 to 14 VDC @ 2.5 A (maximum current draw for a fully loaded NXT-2D/-4D controller).
   

2.1 Current Requirements at 12 VDC

• 650 mA max for an NXT-4D Controller
• 570 mA max for an NXT-2D Controller
• 210 mA max for each NXT-4x4
• 85 mA max for each NXT-1R, NXT-3R, NXT-4R, or NXT-5R Reader
• 115 mA max for each NXT-6RK Reader

• 50 mA max for each NXT-RM Reader Interface Module

• 250 mA max available per bus for use by peripherals

Note: Your power supply must be able to provide the cumulative power requirements for each controller, including all peripherals connected to the controller. Keri strongly recommends using one power supply per controller. Keri also recommends using separate power supplies for the electronic locking devices (magnetic lock, door strike, etc). Should you decide to use the same power supply for both the controller and the electronic locking device, ensure the power supply provides enough current to drive the controller, the locking device, and any peripherals that may be connected (i.e., reader, 4x4, RIM), including an adequate safety margin.

3.0 Relay Contact Rating

1. 1 A @ 24 VDC
   

4.0 Operating Conditions

1. 32°F to 150°F (0°C to 60°C) – 0% to 90% Relative Humidity, non-condensing
   

5.0 Battery/Memory Retention

1. 5-year lithium battery backup to support controller RAM and real-time clock
   

6.0 Cable Options

RS-485 bus runs can daisy-chain together an NXT-4x4 and NXT-Reader on one line. The total cable run distance should be no more than 500 feet from the NXT controller for runs with 4x4s and no more than 1,000 feet for Reader-only runs.

6.1 RS-485 Cable Requirements

RS-485 bus runs can daisy-chain together an NXT-4x4 and NXT-Reader on one line. The total cable run distance should be no more than 500 feet from the NXT controller for runs with 4x4s and no more than 1,000 feet for Reader-only runs.

Recommended RS-485 Cable Types

Connection	Run Length	Purpose	Conductors	Shielded	Stranded	Twisted Pair	AWG
RS-485 from NXT-MSC controller to NXT 4x4 (with or without an NXT 1R/3R/5R reader)	Up to 500 feet (150 meters)	Power	2	N	Y	N	18
		Data	2	Y	Y	Y	22 or 24
RS-485 from NXT-MSC controller to NXT 1R/3R/5R readers	Up to 1,000 feet (300 meters)	Power	2	N	Y	N	18
		Data	2	Y	Y	Y	22 or 24

6.2 Controller Power, Inputs, and Outputs Cable Requirements

Connection	Total Run Length	# of Conductors	Shielded	Stranded	AWG
Controller Power	250 feet [a]	2	N	Y	18
Earth Ground	Shortest path [b]	1	N	N	18
Inputs and Outputs [C]	500 feet	2	N	Y	22

1. To meet CE and C-tick regulations, the length of the controller power line can be no longer than 3 Meters (9.85 feet).
   
2. Use the shortest possible path from earth ground point to PCB. Connect the earth ground only to the designated pin on the terminal block. This is important as all transient protection for the unit is made through this earth ground connection. For unit protection, the earth ground connection should always be made first.
   
3. Values listed are minimums. Individual input and output devices may have more specific requirements.

Notes: 

1. The Lock Output relay may require a heavier gauge of wire depending upon the current demands of the lock and the length of the lock wiring run.
   
2. Cable resistance causes a drop in voltage at the end of long cable runs. Ensure the appropriate power and current for your device is available at the device at the end of the cable run. Heavier gauge cable reduces this effect.
   
3. Keri does not recommend hot-plugging a Reader, RIM, or 4x4 into an NXT controller. Remove power from the controller prior to connecting these devices.

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