Connecting Arduino to Apex BOB without relays

[Harry Muscle]

I'm wondering if anyone has ever connected an Arduino to the Neptune Apex break out box. Based on my reading the break out box should be used with dry contacts like relays, unfortunately they have a limited lifespan. In my case the relay would be activated every two seconds which means it would only last several months.

After more reading I found out that the break out box senses the dry contact as being closed when the connection is completed to ground. An Arduino can pull a connection to ground which should fool the break out box into thinking there's a closed dry contact. However, the problem that I need to overcome is to match the Arduino ground to the break out box ground.

The only way that I can currently think of doing that is by powering the Arduino from the 12V on the AquaBus by creating a custom cable. I know this isn't supported and it's hard to find info on which pins carry the power as well as the maximum amperage available.

I'm hoping someone can assist with figuring this out or even better with an another solution that would work.

Thanks,
Harry

 

[Reefing Madness]

 

[kentofms]

just create a common ground. connect the ground pin on the breakout box to the ground pin on the arduino.

 

[zachtos]

I haven't got my APEX yet, but depends on the GPIO pin voltage. I don't know if it's 3.3V or 5V, either way, what was said above, connect GND on arduino to GND on the GPIO box on the APEX, and the pint you want to control with arduino.
pinMode(pin,OUTPUT); //declare your pin, and share GND
digitalWrite(pin, HIGH); //keep the pin HIGH in declaration and pull to LOW when you want to activate the signal on the APEX

 

[kentofms]

So, just curious. What exactly do you want to accomplish. The breakout box is only good for detecting things like switches. Plus, What is it the apex can't do? its basically a huge arduino with 8 relay sockets. What switch is there that you need an arduino to complete the circuit?

 

[JackOMalley]

First of all, the voltage on the Apex BoB is 24V, whereas the Arduino voltage is 3.3 or 5V depending on the model. The easiest way I could think to do it would be to drive a simple reed relay with the 5V Arduino output that connects a 24V power supply to the input on the BoB. Since there is very little current (milli- to micro-amps) you don't have to worry about having too big a relay.

 

[TheHarold]

You probably know, but make sure to NOT put any voltage into the breakout box. It just uses an extremely low voltage to detect whether any of the SW1 ports close to ground. 12v, 9v, heck maybe 5v in there may do serious damage. I will check the voltage across the switch and ground for you shortly, if you need.

 

[Ranjib]

I am not able to understand what you are trying to achieve. And irrespective of what you are trying to achieve, pretty much all the things you have mentioned can be done easily. You can convert 24v to 3.3V using an LM2596 module (to power arduino), you can use relays, common npn transistors or power mosfets to control hight voltage/current source with lower voltage/current source.
If all you want is to detect mechanical switch interrupts, leak detecters etc.. you can directly do that using arduiono, any reason to involve BoB?

 

[Ranjib]

First of all, the voltage on the Apex BoB is 24V, whereas the Arduino voltage is 3.3 or 5V depending on the model. The easiest way I could think to do it would be to drive a simple reed relay with the 5V Arduino output that connects a 24V power supply to the input on the BoB. Since there is very little current (milli- to micro-amps) you don't have to worry about having too big a relay.

Yup, if the current draw is minimal (Say less than 20ma) you can even use a common npn transistor (like 2n2222a). But this is only for output, not input

 

[Ranjib]

I'm wondering if anyone has ever connected an Arduino to the Neptune Apex break out box. Based on my reading the break out box should be used with dry contacts like relays, unfortunately they have a limited lifespan. In my case the relay would be activated every two seconds which means it would only last several months.

After more reading I found out that the break out box senses the dry contact as being closed when the connection is completed to ground. An Arduino can pull a connection to ground which should fool the break out box into thinking there's a closed dry contact. However, the problem that I need to overcome is to match the Arduino ground to the break out box ground.

The only way that I can currently think of doing that is by powering the Arduino from the 12V on the AquaBus by creating a custom cable. I know this isn't supported and it's hard to find info on which pins carry the power as well as the maximum amperage available.

I'm hoping someone can assist with figuring this out or even better with an another solution that would work.

Thanks,
Harry

On a related note, if you do want to find out what voltages are passing through the aquabus, you can get an usb breakout board, connect a live aquabus cable and use multimeter or oscilloscope to find out what individual pins have.

 

[Bramzor]

So has anyone figured out the best way? I'm currently looking for an easy way that is able to switch a lot (so no relays). Could use solid state relays but probably its even better to just use a mosfet to pull down the signal from the BOB? So all I need is 2 resistors and a mosfet right?