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Physical I/O Connectors and Pinouts

All I/O is via standard RJ-45 Ethernet connectors and RJ-12 telephone connectors. While the NFCS uses these connectors and cables, the signals are not Ethernet or telephone. NFCS cables should never be plugged into Ethernet and telephone equipment and vice versa. The only exception is the NFCS Ethernet connection itself.

There are two conventions for Ethernet conductor color codes - T-568A and T-568B. The NFCS uses the T-568A color codes. As much as possible, power and ground are on conductors that are unused in Ethernet applications to reduce the risk of damage if cables are inadvertently plugged into network equipment.

I/O connectors are mounted in six-port connector plates. Each port can contain either an eight conductor RJ-45 connector, a six conductor RJ-12 connector, or a 4 conductor RJ-11 connector. The standard I/O configuration for each card is designed to map I/O signals within these constraints.

Analog I/O

Standard analog I/O is provided by two AD9700 cards. Each card has eight analog inputs and optionally four analog outputs. To map these into six connectors, the following approach is used:

Connector Type Signals
1 RJ-11 Analog Input 1
2 RJ-11 Analog Input 2
3 RJ-11 Analog Input 3
4 RJ-11 Analog Input 4
5 RJ-45 Analog Inputs 5-8
6 RJ-45 Analog Outputs 1-4

The inclusion of four channels on connectors 5 and 6 means that a breakout box or custom cable must be used for these I/O channels. A breakout box is particularly useful if you have a group of sensors in a remote location such as the roof or an outbuilding. In that case, a standard Ethernet cable can be run from the NFCS to a breakout box in the remote location. Individual sensor cables then are run from the breakout box to each sensor location. This approach may be easier than running four individual sensor cables to the remote location.

Digital I/O

Standard digital I/O is provided by a DIO64 card. Each card has 32 digital inputs and 32 digital outputs. These are mapped to two six-connector panels. Each panel uses six RJ-45 connectors carrying four channels each for a total of 24 channels. The remaining channels can be used inside the controller enclosure. Both the input and output channels are mapped as follows:

Connector Type Signals
1 RJ-45 Channels 1-4
2 RJ-45 Channels 5-8
3 RJ-45 Channels 9-12
4 RJ-45 Channels 13-16
5 RJ-45 Channels 17-20
6 RJ-45 Channels 21-24

Digital inputs are pulled high when not connected, and must be connected to ground to create a condition that can be sensed. A contact closure between a digital input pin and a ground pin is typically the easiest way to accomplish this.

Digital outputs are typically used to drive relays or LEDs. The are 'floating' when not activated, and act as a connection to ground when active. Typically a load such as a relay coil is connected between +12V and a digital output pin.

RJ-45 Pinout Table

The pinout is driven by the desire to put power and ground on pins that are not used in Ethernet cables. In the cases where there are multiple pins with the same signal, they are electrically interchangeable.

Pin T-568A Color Analog I/O Digital Input Digital Output
1 Channel 1 Channel 1 Channel 1
2 Channel 2 Channel 2 Channel 2
3 Channel 3 Channel 3 Channel 3
4 Ground Ground +12 V
5 +5 V Ground +12 V
6 Channel 4 Channel 4 Channel 4
7 +12 V Ground +12 V
8 Ground Ground +12 V

RJ-11 / RJ-12 Pinout Table

Pins 1 and 6 are used for thermistor sensors. They allow the required scaling resistor to be crimped into the RJ-12 connector so that it's part of the sensor cable assembly.

There is a change between version I and Version II conrollers. In Version II, the variable speed (4-20ma) drive is inside the controller rather than in an external breakout box. The 4-20ma signals are present in the RJ11 analog output pins, in the position fermerly used for the staright 0-5V output.

RJ-12 Pin Color Code 1 Analog Input Analog Output Digital I/O Color Code 2 RJ-11 Pin
1 +5 V +5 V    
2 Ground Ground | V2: 4-20ma- Ground 1
3 Input N/C | V2: Ground Input 2
4 +12 V +12 V | V2: Output +12 V 3
5 +5 V Output | V2: 4-20ma+ Output 4
6 Channel 1 (dup) N/C | V2: +12 V