I'm looking to integrate all those signals into a single serial output at c. 1hz, possibly using RS232 but will be communicating over 100m of cable so RS485 would probably be better?
Was thinking of the Adafruit Trinket Pro but open to any other recommendations, particularly around the most reliable way to do the serial output.
Connecting multiple sensors (of whatever type) via I2C is what I2C is made for so that should not be a problem. If you have not yet used an Arduino with I2C there are countless examples both here on this forum, in the Arduino playground and elsewhere for you to experiment with. Get one working before attempting to connect multiple sensors. Note also that each device must have a unique hexadecimal address, but some devices allow you to modify that address (to a degree) so the same or similar devices with otherwise identical addresses can be used simultaneously.
I'm guessing you didn't mean 1Hz serial output but 1kHz? What is the Arduino communicating with? You could do it wirelessly if you're talking about 100m - that's a lot of cable!
Finally, you mention the Trinket Pro, one of Adafruits variants of the Arduino but not why you favour that one? What's wrong with a standard Arduino Uno which is easier to handle and has a built in USB to serial device on board (which the Trinket Pro doesn't and hence is a limitation which might affect you). Just wondering!
To get better, more targeted responses, you could submit a simple drawing of your intended design so that we can understand the goal of the entire project rather than just bits and pieces of it - a neat and labelled hand-drawn diagram, photoed and uploaded would be ideal.
It sound quite exciting what you want to do so please do post back
Thanks for the replies so far and sorry for my slow response.
-This project is intended to be a submersible ( up to 100 m) sensor package.
-The Arduino will need to be waterproofed (potted inside an enclosure?), hence I was looking at the Trinket Pro due to its small size; but open to alternatives.
-By 1 Hz, I mean I want the arduino to send a line of text over RS232 every 1 second.
-Here is a quick diagram of the setup:
I also have a specific question about one of the sensors I was looking at (Hamilton Visiferm, too large to attached but can be found by Googling "hamilton visiferm DO manual"). It's a process sensor and as such is 24V, but gives a range of 7 - 30V so presume it will operate OK at 12V supply? Also, I was planning on using the 4-20mA output (with precision resistor to convert to 1-5V), but there is a bunch of detail in the manual about the 4-20 mA (pp17 - 19 of manual) using PWM to acheive the 4-20mA range and hence requiring galvanic isolation from the power supply.. I am not sure if and how this affects the feasibility/complexity of reading this sensor's 4-20 mA output using the ADS1115 ADC? There are other, potentially simpler options for optical DO sensors, but none of the others have the combination of small form factor and pressure tolerance of the Hamilton.
The datasheet does not explain whether 12v is suitable. I think it is saying that anything between 7v and 30v won't destroy the device and it is definitely saying that it will work at 24v.
What voltages does a 4-20mA ouput work at? Maybe that needs 24v to ensure it can reach 20mA ?
Yeah that was my concern too.. I have contacted the distributor for advice on whether 12V supply will work or not.. if not I suppose something like this could do the job Pololu 24V Step-Up Voltage Regulator U3V50F24 ?
