I am trying to wire a D6 strain-gauge dendrometer (http://library.metergroup.com/Manuals/UMS/D6_Manual.pdf) to a multiplexer (AM16/32B) but I am having a hard time to do it (even reading the manuals). Could anyone give me any instruction on how to do it?
From my understanding to wire to a datalogger would be:
Red -> Vx1
Black -> ground
Green -> 1H
White -> 1L
Following this idea, I have wired the Green (1H) and White (1L) to the AM16/32B. I was wondering where the Black and Red would go in the AM16/32B?
Thank you so much!
Being full-bridge, you will be using the AM16/32 as a 16-channel. I believe you need
Excite + to 1H
Excite - to 1L
Signal + to 2H
Signal - to 2L
Have you used Short Cut before? You may want to use that to get started since it gives wiring help and has questions for settings to get the program set up correclty.
Start a new program, select the AM16/32 and select it, then select the Full Bridge Strain 350 ohm and add that. I don't know all the other settings you will need.
Hi Terri, thank you so much for the reply!!!
After reading the D6 sensor manual a couple of times I realized that it has a TensioLINK which transfer the full-bridge sensor as SDI-12. So, I would have to change the address of the SDI-12 to connect to one port on the CR300. I will not be able to use the multiplexer in this case, because CR300 does not have another port (C3) to receive the output.
Since I do not want to connect all the sensors to one port, I was actually planning to get a CR1000X so I would be able to use with the AM16/32B. I was wondering if I could use SDI-12 sensors with the multiplexer + CR1000X, even though the sensors require an excitation of 12 V (SDI-12). Using a short-cut, it gives a wiring connection for SDI-12 to the multiplexer + CR1000X, but I just found interesting because reading the multiplexer manual, it says that the multiplexer can not multiplex power:
"The AM16/32B is not designed to multiplex power. Its intended function is to
switch low level analog signals. Switched currents in excess of 30 mA will
degrade the relay contacts involved, rendering that channel unsuitable for
further low level analog measurement. Customers who need to switch power
are directed to Campbell Scientific’s SDM-CD16AC, A6REL-12, or
A21REL-12 relays."
Would you have any idea if it is possible? Thank you so much!
Jessica,
If you are connecting an SDI-12 sensor to an AM16/323 multiplexer, I would not multiplex the power, only the signal. An sdi-12 sensor just has one communication line and then ground wires. The communication (data) line is the only line that you would really need to multiplex (you would want to wait long enough to get the measurements back before switching th the next channel).
Wiring between the multiplexer and the CR1000X for just multiplexing one channel would be:
CR1000X C7 (or any other odd control port) to COM ODD H
CR1000X G to COM analog ground (ground symbol between the COM ODD and COM EVEN terminals)
I would create a power terminal bus for SW12 1 and SW12_2 for turning the power to the sensors on and off. You would just need to verify that you do not exceed the SW12 power output capabiilty.
If you want to control power to each sensor individually, then you will need to get a different relay module as mentioned previously.
Programming would require using two of the control ports of the CR1000x for powering on the multiplexer and clocking (moving the channel) on the multiplexer. So you will need to turn on the multiplexer, clock it to the first channel, turn on the sensor, send it a request for data (using the SDI-12recorder command), delay long enough to get the data, then clock to the next channel and repeat the process.
If you would like to take advantage of Campbell Scientific expertise, they have personnel that can write a program and generate a program for a relatively modest fee.
Hi Uplander
Again thank you so much for the reply. The SDI-12 sensors have three wires interface: Serial data line, Ground line, and 12-volt line. I will study this possibility of getting a CR1000x because it looks more appropriate for my case. Also, I like the idea of having a personal to do the program. For now, I will try to wire the SDI-12 sensors on ports C1, SW12 and G on the CR300 datalloger and see what I get. Thank you so much for your assistance