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Cannot connect TDR100 with SDM8X50

sebnemboduroglu Feb 4, 2019 08:33 AM

Hello all, 

I am trying to come up with my TDR100 System and so far I could not make it work. I am using CR3000, TDR100 and SDM8X50 and CS640 probes. When one CS640 is connected to SDM8X50 through Channel I, it gives logical waveforms and VWC values. However when I move this probe to other channels, for some reason it gives a unexpected waveform with cable length reduced to 3 m, which is not the case. I am suspecting that the pulse does not even reach to other channels of the multiplexer. I am using the SDM address of 0 for TDR100 and SDM address of 1 for multiplexer. I am lost on how to solve this problem and I would appreciate all the help that you can provide me.

Thank you,


Notso Feb 4, 2019 03:00 PM

Hello Sebnem,

It sounds like the multiplexer is not advancing through its channels. Please check to make sure the voltage between 12V and G on the SDM8X50 is the same as the voltage between 12V and G on the CR3000. Also make sure that all the channels labeled "C1" are well connected to each other. Check also that all "C2" channels are connected to each other and all "C3" channels connected to each other.

The SDM address of the SDM8X50 should be one number higher than the address of the TDR100. If the TDR100 address switch is set to 0, then the SDM8X50 address switch should be set to 1.

Please email me at jritter@campbellsci.com if none of these checks identifies a problem. 

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