Strain gauge

[Dr._Imad]

I have a PCI-6224, SC-2345, 2 cables, 2 SCC-SG01 quarterbrige strain gaue modules.
Win XP Max 3.1, Nidaq 3.0
I am using the first set of channels 0-15 , to read analog voltage data (connected thru SCB 68 to terminal 1 of PCI-6224). The SG01 modules are put in SC-2345 slot J1 and J2. I configured the SC-2345 thru Max. The SC-2345 is connected to the 6224 daq card thru terminal 2.

I used daq assistant to generate a typical vi to read strain gauges.

question,1
how does daq assistant know that the SC-2345 is connected to terminal 2 and not 1. that is , the analog strain gauge channels read are 16,24, 17,25, as opposed to 0,8, 1,9 ? Currently, it uses syntax like SCC1/Mod1/ai0 etc

question 2,
Instead of worrying about configuration and all of that, and SCC1/Mod1/ai0 and all of that, can I simply treat the SG modules as simply output modules, that is
configure all my analog input channels as NRSE (range -10 to +10 V)
then read my analog voltage data, read all the channels that I need, including the SG01 channels (as dev1/ai16,dev1/ai24,dev1/ai17,dev1,ai25
and, then for the SG voltage data, I divide by 100 (because the SG modules have a gain of 100)
then use the calculated (divided) voltage as input to a the "convert strain gauge reading.vi", and calculate the strain (assuming my input data is set properly ; excitation voltage, bridige configuration, etc...

[George M.]

Hi,

1) The pins match up between both connectors. That is, the analog input pins are the same on both terminals. The only difference is if it is AI 0-15 (Connector 0) or AI 16-32 (Connector 1). The AI0 on the end of the SCC1/Mod1/ai0 refers to the connector on the SC 2345 not the actual connector you are using. This is because the M Series boards are the first devices to have multiple connectors, so this was not an issue in the past. So, even though you are using Connector 1 (AI 16-32) the device string will still be SCC1/Mod1/ai0:15.

2) You can definitely use Dev1/aiXX as your string to call particular channels on the SC 2345. That is, if you are using Connector 0, then you will be using AI 0-15. For Connector 1, you will obviously be using AI16-32. You are also correct in that you will have to do the scaling in software as you mentioned.

I hope this helps. Have a Great Day!

George

[Dr._Imad]

This is what NI support said about recognizing bothe terminals (connectors of the M series Card)

"To answer your question:
1. How does NI-DAQ know that the SC-2345 is connected to terminal 1 or 2?
That is indeed a very good question. From M-Series (PCI-6224 is part of
it), you can connect two SC-2345 to one M-Series DAQ board. However, it's
going to be supported from NI-DAQ 7.4 which is going to be released soon.
Therefore, at this moment, you should connect SC-2345 to the terminal 0 of
the PCI-6224 board in order not to lose some of the functionality (ex.
counter/timer or analog output) of DAQ board even though it works fine for
analog input. There is a relative KB. Even if it's about E-Series board,
it'll be same for M-Series before NI-DAQ 7.4. Please refer to the below
link for more information.
http://digital.ni.com/public.nsf/websearch/5000D181F76162FF86256A3B00562560?OpenDocument
"

So, it is going to be supported in Nidaq 7.4. Just to share the info.