Opto-isolated inputs

Each main panel provides four opto-isolated inputs using the GPIO interface.

Each input consists of a pair of pins on the GPIO with an operating range of 4V to 30V DC or AC. These inputs can be used for user programmable functions set up by EHX to execute other actions within the system such as switching a microphone on or off.

Input 3 (pins A3/B3) is preassigned in EHX to trigger the Reply Key function while inputs 1 and 2 (pins A1/B1 and A2/B2) are available for assignment in EHX in Advanced Settings > Logic Inputs.

Input 4 (pins A4/B4) is not currently used.

The inputs are operated by applying a voltage between 4V and 30V DC or AC across the pins so that a current flows through the circuit and is detected by the opto-coupler.

The voltage may be derived from the panel itself using the 5V and 0V pins on the GPIO or it may be from an external source. An example is a circuit using a footswitch to activate the panel microphone using logic input 1.

In the above example, pressing the footswitch applies 5V DC from the panel between B1 and A1. This enables the detection of a logic input.

If logic input 1 has been configured in EHX to activate the Mic On/Off function the footswitch could be used to control the panel microphone.