Thought I'd post a solution for anyone looking for a way to use a non-contact (contactless) fluid level sensor with the Neptune DOS 6-pin molex port. Refer to this post (
https://www.reef2reef.com/threads/apex-dos-diy-level-switch.246352/post-2897212) for pin numbers on the DOS connector. The problem I and at least one other user
@nunoml were having was that unlike the DIY optical sensor, the DIY non-contact sensor was not triggering the switch in the Apex.
First, why a non-contact switch? Perhaps you are using a disposable container or a solution that may not be suitable to leave an optical sensor submerged. I am using them for monitoring a Heinz vinegar (carbon dose) jug, a gallon hydrogen peroxide bottle, and a DIY frozen food dosing container (I can elaborate on this separately if anyone is interested). For the first two uses, the jugs can easily be replaced when empty and the sensor is just moved to the new bottle.
There are basically two types of sensors easily obtained from Amazon or similar (there are many sellers selling the same thing so just find the best price):
1. The XKC-Y25 version, good for flat surfaces:
https://a.co/d/ficCrYb
2. The XKC-Y26 version, good for zip tying to curved surfaces/pipes:
https://a.co/d/guN2t7b
The wiring is different than the optical sensors used in this thread. On the sensors, the brown wire is a 5V input (comes from pin 1 on the DOS plug). The yellow wire is switch output (goes to pin 3 or 5 on the DOS plug) and the blue wire is ground (goes to pin 6). The black wire can be ignored or if you connect it to the blue wire, will switch from normally-open (NO) to normally-closed (NC) (i.e. the behavior of the sensor when there is liquid present is reversed). Both sensors have built-in LEDs so there is no additional wiring needed for those.
The issue with using these (I least my best guess) is that the current is so low that when the built in relay in the sensor is switched, it is not enough to be detected by the DOS. The solution is to use an external, low current relay. I used this relay (
https://a.co/d/0MwNw90) which allows for two inputs/outputs (2 channel) so one of these will be good for both sensors on the DOS. I have two DOS, so the two pack was perfect. You need to switch these to be low level triggers to make it work with the DOS. This is easily done by just shifting the jumpers on the board (they are yellow in the picture below). Then you just wire it up.
1. 5V out from the DOS (pin 1) goes to the following locations: brown wire from sensor, DC+, COM1, and COM2.
2. Ground from the DOS (pin 6) should be connected to pin 4 in order to get the tiles in Apex Fusion (I didn't use a resister as discussed in this thread) and connects to the following: blue wire from sensor, DC-
3. Input 1 wire from DOS (pin 3) connects to NC1 (if it doesn't work, try NO1)
4. Input 2 wire from DOS (pin 5) connects to NC2 (if it doesn't work, try NO2)
5. Yellow wire from the sensor connects to IN1 or IN2 (one of each sensor if you use two sensors)
A few things to make it all look pretty:
1. A watertight box to hold the board and contain the wires:
https://a.co/d/fo8FptV. I used a drill to cut out openings in the lid for female molex connects I made (see pics).
2. A XH2.54 no-crimp molex connector kit. The sensors have XH2.54 molex plugs so you can just make some female plugs for the box to connect to:
https://a.co/d/drKX1W8
3. 4 pin, XH2.54 molex extension cables so you are not limited by the length of the sensor wire:
https://a.co/d/9Rmkvct
4. 6 pin micro-fit 3.0 to free wire connectors for easy wiring to the DOS port. I then connected these to a male XH2.54 6-pin plug which plugs into the female 6-pin plug on the box (see pics). Makes it easy to disconnect everything:
https://www.newark.com/molex/214756-1061/wtb-cord-micro-fit-rcpt-free-end/dp/65AH2747?ost=65ah2747
I don't mind soldering, but the relay board doesn't require it as all connections are screw terminals. The terminals really only hold two wires each, so you have to get creative to get all the 5V wires connected together. You will need to crimp or solder the XH2.54 connector to the connector going into the DOS.
Here are some photos of the relay, the wire between the DOS and the relay box, and the box itself with female plugs (the two on the left are for the sensors and the 6pin on the right is for the wire to the DOS). I was sloppy, but it gets the job done. I tried using one of these on a skimmer cup, but even after adjusting sensitivity (via the screw on the side of the sensor), the fluid in the neck of the skimmer often triggered the sensor.
Happy to provide more details to anyone interested.