Appendix 3: GPIO Connection

The GPIO connector is Micro-Fit 3.0™ 2 x 7 position 3.0 mm pitch connector manufactured by Molex

(http://www.molex.com) .

Digital inputs have pull-down resistors. All general purpose I/O (GPIO) pins (i.e. all input and outputs) have transient protection.

 The I/O port provides for the control of 4 external devices and for monitoring 4 external inputs.

GPIO Output Connection

The 4 outputs are configured as “open drain” which means that they can be directly connected to energize external relays, lamps, or other DC devices.

 Maximum supply voltage is 36 volts, with a maximum load current of 500mA.

 Recommended wire gauge for use with the connector is 20-24 AWG. Note that the OUT GND connection is connected to the CTM-ONE’s supply ground.

Open

GPIO Input Connection

The 4 inputs may be configured in the CTM-ONE for monitoring a digital DC voltage state or an analog DC voltage. All of the inputs are single ended.

For digital state monitoring, the minimum input voltage is 0 volts while the maximum is 36 volts.

The threshold detection voltage is 2.5 volts with 1 volt of hysteresis. Note that the IN GND connection is referenced to the CTM-ONE’s supply ground.

 Analog input values will be sampled and can be reported at a maximum frequency of 10Hz.

Example of Digital Input wiring

Open

For analog voltage monitoring the measurement range is 0 to +10 volts with 10mV resolution. The input can withstand up to 36 volts. Note that the IN GND connection is referenced to the CTM-ONE’s supply ground.

Example of Single Ended Analog Input Wiring