DBR_Reef
Active Member
I’m going to be doing some videos on alternative sensors to use with the ASM module. This is the module that comes with the par meter or PMK, but you can purchase them separately if you contact Neptune directly- they are about $100. In my opinion this is probably the most under used Neptune product. Basically, any sensor can be adapted to be integrated with an apex.
While there are many uses for the ASM module, perhaps the most relevant is the humidity sensor. Maybe you want to control an exhaust fan in a stand or fish room, or simply want to make sure that your dehumidifier is working. While there are far cheaper humidity control and sensor options, none will have the remote monitoring or easy viewing of being integrated with your apex.
So for this we need:
ASM module- these accept a 0-1v or 0-5v input
24v power supply- any generic 24v dc power supply will work. However, if you have a EB832 with a spare 24v accessory port a 24v cable is a nice, clean option. https://www.bulkreefsupply.com/dc24-to-bare-wire-accessory-cable-neptune-systems.html
Humidity sensor: There are MANY options available here, but to make things as easy as possible I looked for one that had 0-5v out as the signal. There are many sensors that use 0-10v or 4-20 mA signals- these can be used but require some extra electronics/wiring, so why bother. I can’t recommend a particular seller on ebay, as the guy I bought it from lied to me, but if you search “humidity 0-5v” on ebay, it should pop right up and cost about $15. There are many more expensive humidity sensor options, including ones that have displays built in, but these work fine. If you use a different one, as long as it is 0-5v signal the wiring is the same.
Coax cat5 To BNC adapter: these are available all over eBay for less than a buck
Some wire: I’m using doorbell wire.
To wire it up, all we do is take the + and – wires of the power supply and insert them into the + and – terminals on the humidity senor, then take your spare wire and connect the positive into the humidity terminal, and the negative is going to share the power supply negative. Then take your signal wire and insert the the + and – wires into the corresponding terminals of the BNC connector. Keep this wire reasonably short, as the voltage will decrease with length, affecting your readings. The amount varies depending on amps and wire gauge, quality, and length- it is easily calculated, but I don’t see any reason to have longer runs than a few feet, at which point the change is negligible.
Now we need to program the ASM- so plug it in and go to the modules page. Click on the asm module and change it from par to 0-5v signal. Set the minimum to 0 and the max to 100. Plug the bnc connector into the ASM module and you are all done- it is reading humidity in % relative humidity- and you can use it to set alarms or a on off of a fan, or whatever.
Lastly, you want to place the humidity sensor carefully- these sensors are susceptible to corrosion and should be kept well away from salt spray. They should also be placed in a representative location with decent air flow. They certainly don’t need a fan blowing on them, but if you want it to measure humidity in a room, putting it in a corner covered with junk is not going to work.
Thats it!
I've noticed that chinese sensors tend to be fairly precise, but very inaccurate. So for relative changes they are fine, but the actual numbers are bogus.
