Hello,
I have have a CR350 with two turbidity sensors. The other analogue channels are being used so I'm trying to put both of the turbidity sensors into one channel. The turbidity sensors only need three wires connected; ground, 12V power, and a signal which can go in either the H or the L of the channel.
I can get both turbidity sensors to turn on but I think that because both are outputting there values into one channel it gives me one reading for both of them. Is there a way that I can seperate the two signals coming into the channel so I can get readings for both? Or would it be better for me to look into getting an analogue to digital converter and then wiring it into a com port?
Thanks,
Dave
The CR350 has two Switched (on/off) 12 V channels - SW1 & SW2. You could try powering the sensors separately with these two channels, rather than powering them both with the 12V channel; i.e., Turn on SW1, measure the channel. Turn on SW2, measure the channel.
There would be considerations, some of which will likely make what you are trying to do not feasible.
* When turning on the sensors, you would need to take into consideration any warm-up period your sensors need.
* All readings will be stored in one variable/accumulator, which means that the only output that you would realistically see in the Public table or stored in a data table is the "last" (second) measurement, unless you program around this (grab the measurement and store it elsewhere before it gets overwritten by the next measurement). Additionally, you would only be able to take a Sample of the measurements, since the same memory space would be used for both sensors (so Average, Max, Min, etc. would not work). This may not be an issue with a turbidity sensor.
I don't have any experience with using converters in this kind of application.
Best, Dana
Did you already look at VoltSE (Single-ended channel) instead of VoltDiff (differential channel) ? When using SE measurements "H" is considered to be one channel and "L" is a different channel (SE channel numbering 1, 2, 3, 4 for analog, vs. Diff 1 and Diff 2 - H+L pairs)
We are reading from two different analog pins on the arduino. They do have the same ground potential.
Alternatively you could also use a shunter relay controlled by a sw12v port or via a simple power circuit via a control port.
The common of the relay connected to the logger channel, the NC to one probe and the NO to the other probe.
Obviously a sealed relay and with very good specifications.
You can normally read the connected NC probe and after turn on the sw12V (or control port) to read the second probe on the NO contact and then turn off the sw12V (or control port)
With a small expense you will have the advantage of having the 2 probes electrically separated.
Furthermore, with more expense but a great potential for future use, you could also use the AM16/32 model. You can greatly expand the inputs of the logger
Smile