1.0 Wiring and Layout Diagrams
1.1 NXT-4x4 I/O Module
Note: This equipment has been tested and found to comply with the limits for a Class A digital device, pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference when the equipment is operated in a commercial environment. This equipment generates, uses, and can radiate radio frequency energy and, if not installed and used in accordance with the instruction manual, may cause harmful interference to radio communications. Operation of this equipment in a residential area is likely to cause harmful interference in which case the user will be required to correct the interference at his own expense.
Table 1: 4x4 LEDs
2.1 NXT 4x4 Dimensions
• 4x4 PCB
- 5.25 inches tall by 3.10 inches wide by 1.00 inches deep, not including wiring connectors
- 13.33 cm by 7.87 cm by 2.54 cm
• 4x4 Enclosure
- 8.00 inches tall by 7.00 inches wide by 2.75 inches deep
- 20.32 cm by 17.78 cm by 6.98 cm
2.2 Power Requirements
• 10 to 14 VDC @ 0.5 A (maximum current draw for a fully loaded NXT-4x4).
2.3 Current Requirements at 12 VDC
- 250 mA max for each NXT-4x4
Note: If you are driving an electronic locking device (magnetic lock, door strike, etc.) using the same power supply as the 4x4, ensure the power supply provides enough current to drive every device connected, including an adequate safety margin.
• 1 A @ 24 VDC
2.5 Operating Conditions
• 32°F to 150°F (0°C to 60°C) – 0% to 90% Relative Humidity, non-condensing
3.0 Controller/Module Grounding
To ensure optimum earth-grounding of the NXT controller and its connected peripherals, you should make a quality earth-ground connection to the metal enclosure lug (which displays an adjacent earth-ground symbol).
This good-quality earth-ground at the enclosure lug will provide an earth-ground for the entire enclosure - and will therefore ground anything that is connected to the metal enclosure - (the four metal screws at each corner of the PCB) - plus, through circuitry on the PCB, this includes anything connected to the lug marked J6 or pin 3 of the TB10 power connector.
In addition, the enclosure itself must be earth grounded to a good quality ground point external to the enclosure for a complete path to ground.
Also, the shield/drain wire of any reader/peripheral cables MUST be terminated to one of the following points-any corner screw attaching the controller to the enclosure, Pin 3 of TB10, the green ground lug (J6) on the controller, or the ground lug of the enclosure. Failure to properly earth ground the reader/peripheral drain wire may result in unreliable communication or operation of the attached peripheral.
4.0 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 less than 500 feet from the NXT controller for runs with 4x4s and less than 1,000 feet for Reader-only runs.
4.1 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 Type
- 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 affect.
- 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.
4.2 Controller Power, Inputs, and Outputs Cable Requirements
Total Run Length
# of Conductors
250 feet [a]
Shortest path [b]
Inputs and Outputs [C]
- To meet CE and C-tick regulations, the length of the controller power line can be no longer than
3 Meters (9.85 feet).
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.
- Values listed are minimums. Individual input and output devices may have more specific
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.
- 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.
- 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.
4.3 Earth-Ground Cable Requirements
- Single conductor, AWG 18 wire (or a larger gauge). Ground wire is green with or without yellow tracer.
P/N: 01998-001 Rev. H