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Getting Started on Connecting a Load Cell to a 9148 Expansion Chassis

Hello,

 

I'm a Civil Engineer that's begun my thesis on a large scale (1m) direct shear apparatus. I've been provided with a number of DAQ hardware modules and the 9148 Expansion Chassis, but was looking for some insight on how to hook up and test one of the load cells I will be using before I transport the hardware to the site (which is rather remote). Most electronics are outside the scope of my undergrad education, but I have made a bit of progress on my own.

 

The 9148 has been sucessfully connected to my machine and the MAX software, and software has been installed to the chassis.

I have 5 modules seated inside the 9148, (2) 9223 (2) 9237 and (1) 9213.

 

Now, I'm concerned with hooking up the load cell seen here and testing the data acquisition. Overall, I will have 4 load cells hooked up to the chassis.  I'm fairly certain that I need to hook up the cell to the 9223 module, but am not sure which of the wires seen in the load cell image I should use.

 

Thank you for reading, and for the possible help with my dilemma.

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Message 1 of 11
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You should hook them to 9237. Page 10 of http://www.ni.com/pdf/manuals/374186e.pdf shows how could you do it.

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Thanks for the reply! But I'm afraid it left me even more confused. I have basically zero EE knowledge, so I have no idea how I'd begin to hook those 5 wires up to a 37 pin DSUB connector.

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Hello tsrobinson,

 

Are you using the NI-9237 with the RJ50 connectors? If so you can follow this article for wiring your sensor:

 

http://digital.ni.com/public.nsf/allkb/892C84122A6501AE86257547007E5C53

 

Regards,

 

-Travis E

National Instruments
Product Marketer
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Unfortunately, I'm using the 9237 with a 37 Pin connection, not the RJ50. Seems like the RJ50 would make my whole job a lot easier, but I wasn't around when they ordered the hardware. Any tips?

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Hey tsrobison,

 

Can you post a pin out for the sensor? I am not sure what the green wire is referring to, I want to confirm what each wire is for the sensor.

 

Regards,

 

-Travis E

 

National Instruments
Product Marketer
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Message 6 of 11
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I think this is what you're looking for - 

 

White - Ai-

Green - Ai+

Black - Ex-

Red - Ex+

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Message 7 of 11
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The 9237 provides excitaion, remote sense, and an analog input for your sensor.  You will need a 37 pin d sub cable and a 37 pin d sub termnal block to connect to the module (phoenix contact will have some stuff but NI will sell you connectivity equipmet).

 

You need to wire the following:

 

Ex0+  Red Pin 2

Ex0- Black Pin 21

Sig0+ Green Pin 3

Sig0- White pin 23

 

Jumper the Ex0+ to RS0+ Pin 1 and the same for EX0- and RS0- on pin 20.  This will allow the module to compensate for any voltage drop from the test leads as best it can.  There are more optimal ways to wire it but you can experiment with that on your own.


You can select the excitation to use and the module will power up the load cell.  You can then program the acquisition and stream the data to your host .  The 9148 is an FPGA chassis so use DMA for high speed acquistiion and streaming.


This should get you going with the 9237.  The data sheets spell out most but post any questions if confused.


Adam

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Thanks for taking the time to respond. At the moment, I have 2 9237 modules loaded into my 9148.  The 37 pin conductor is then opened and connected to a cat5 cable (seen here with one completed connection and one yet to be completed). The cat5 cable then connectes to the loadcell via a keystone seen here

 

Does this seem like a reasonable way to get everything connected, or would there be too much of a drop across all those connections to get power to the cell?

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Yes that will work.  I apologize I thought you had the 37 pin version, not the RJ-50 version.

 

You will accomplish the same thing except use the keystone.

 

Wiring:

 

EX0+  Red wire to pin 6

RS0+ Jumper wire from pin 6 to pin 4

EX0- Black wire to pin 7

RS0- Jumper wire from pin 7 to pin 3

AI0+ Green Wire to pin 2

AI0- White wir to pin 3

 

Choose your excitation that the module will output, set up your task, apply a load and record some data.  You should be off and running now.

 

http://www.ni.com/pdf/manuals/374186e.pdf

 

Refer to page 6 for wiring.

Best,


Adam

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