HD-4Opto-4R (4 Isolated inputs) & (4 Isolated Outputs/Relays)

for any BrightSign units w/GPIO

4 Isolated inputs (Buttons) via Opto-Couplers and 4 Isolated outputs (Relays) 

HD-4Opto-4R   ,Opto & Relay I/O Board

Features:

• small footprint (3.2 x 3.0 inches)
• Can mount directly to the DB15 connector or use a DB15 extension cable
• 4 Opto-coupler inputs (some call them solid state relays).  For use with 12 and 24 volts remote activation devices.
• 4 Relays for Isolated Outputs
• New Rev 2 board uses inverted GPIO signals so relays don't turn on on power-up!
• Requires 12V external power supply (2.1mm jack available on board or direct connect to the terminal block).

This board solves the need for using a relay to convert a control signal of 12 or 24 volts DC to a switch closure.  The BrightSign only works with 'switch closure' to 0Volts to activate the GPIO inputs.  The opto-couplers convert the 12 or 24 volt input to a 'switch closure' to operate the GPIO inputs (BTN0-BTN3).  When the voltage is applied to the opto-coupler, the output of the opto-coupler turns on (same as closing a switch to the BrightSign)

There are two terminal blocks for inputs.  One terminal block is used to control the 4 Opto-Couplers (see schematic).  The other terminal block allows for bypass of the opto-couplers so that normally open switches can be used as well.  The opto-couplers are like normally open switches so you can parallel the output of the opto-coupler with a switch using the second terminal block as inputs

Opto-Isolator Inputs: There is an 8 pin terminal block marked with +V and 0V for each of the 4 inputs.  The 4 inputs are labeled 0-3 (this corresponds to Btn0-Btn3 of the BrightSign).  This board is utilized when another device applies 12 volts or 24 volts to turn on a remote device (the BrightSign).

The new Rev 2 board uses 'low signals' to turn on the relays.  The BrightSign powers up with the GPIO's all set to inputs with internal pull-up resistors.  The GPIO has all 'high' signals to the relay turn-on circuits.  The new board takes care of the relay problem (all on when power is applied) by inverting the GPIO signals that control the relays.  Now set the GPIO (4 - 7) low to turn on the associated relay.
Gpio-4 low, turns on K1
Gpio-5 low, turns on K2
Gpio-6 low, turns on K3
Gpio-7 low, turns on K4

Note: Relay outputs are just a closed set of contacts.  See the schematic for connecting 12V or other external voltage to the contacts to control external devices.

Important: It may be necessary to add a snubber network across the terminal blocks when switching AC loads.  The 'electrical noise' of relays switching could reset the BrightSign.  The 'snubber' network should be a 100 ohm 1/2 watt resistor and a .022 micorfarad capacitor in series.  The capacitor voltage rating needs to be 2.2 times the applied voltage.  I.E. for 230V, the capacitor should be rated to 500 volts.

Important: For DC loads, a diode has to be connected across the load (see the schematic)

Note: Snubber Networks are available on the ordering page for this product.

Link: Schematic

Updated: 03/02/2024