I am wondering if there is a way to put to sleep a single sensor as opposed to the entire data logger?
Here's my situation:
I have a CR1000-based weather station with numerous sensors that is currently operating in the field. In the near future I will be installing a multiplexer to run six thermal dissipation probes (TDP) that will be used to measure sap flux and, ultimately, transpiration in pine trees.
These units require significant power to generate heat for the probes, and I would like to shut them down overnight (when there is little transpiration) to save power. However, I would like the other sensors to remain operating. The TDPs are connected to the CR1000 via a multiplexer.
Does anyone know if this is possible or how to go about this?
Thanks,
Jim R.
Hi Jim,
What you would want to do is use a control port and a relay to turn the power off to the heaters. If you are using the adjustable voltage regulators from Dynamax I am pretty sure they have a power control built in.
However, I don't think you are really going to want to turn them off at night because the TDP method requires you to have data at a time when you can assume zero flow, night-time for most people.
Cheers,
Bill
Hi Bill,
Thanks for the response. You are correct, I do need a minimum temperature differential (dTM) from the overnight period. However, I believe I could just take a single overnight reading and let the system sleep the rest of the night. These are option described briefly in the Dynamax manual.
I do not have much direct experience coding in CRBasic besides some tweaks here and there to SCWin generated code. Do you have any thoughts on were I might find a program template to get the behavior I'd like?
Thanks again for the help,
Jim
Hi Jim,
I am not aware of any program templates and it looks like Dynamax doesn't have any either. If you are purchasing the TDP's from them they might be able to help you out with a program. The instruction you will probably want to use is the IfTime instruction, I'm assuming you are using a CR1000. Then you can use the PortSet to turn the voltage regulator on and off.
I would suggest that you might want to have it on all night once per week or so. The reason being that depending on the species of trees you are working with and the environmental conditions dTM might not occur for several hours after dark or might not occur at all in some trees with leaky stomata. Just my two cents :)
Cheers,
Bill