01-07-2010 10:18 AM
I am using for the first time a 6225 PCI card (80 analg inputs). This card is linked to two SCB-68 bloc junctions and my purpose is to use it to acquire 40 différential signals. Using the DAQ assistant I have come up to these conclusions :
1) The first 8 of my 40 différential inputs go onto the first bloc junction?
2) On bloc junction n°1 for each differential signal I need to put a 10 Kohms biais resistance between each AIGrnd and the V(-) of the signal. This is what I have done with other 622X cards. In order to do this with bloc n°2 too, I only have pin n°22, 9 and 43 free to use for all my 32 signal. Is this correct?
I know these are 2 very basic questions but if somebody could just answer them for confirmation it would be great.
Thanks a lot,
Solved! Go to Solution.
01-11-2010 04:47 AM - edited 01-11-2010 04:48 AM
1) The first 8 inputs go onto the 1st bloc junction as this pdf for connector 0 shows. For the last pin on the connector 1 you will find the information in the screenshot below :
2) Depending on your source impedance, you should connect your source as described in figure 4-5 :
Or 4-6 of M-series user manual (page 4-15 to 4-18, thus, with a coupled bias resistor also between the positive lead of the source and AI GND).
Thereafter if you have some noise problem , you could follow these documents:
How Do I Eliminate Ghosting From My Measurements?
Decreasing the Source Impedance of an Analog Input Signal
Using a Unity Gain Buffer (Voltage Follower) with a DAQ Device
I hope this helps.
01-11-2010 04:46 PM
- I am sorry but I don't understand what is special about the last pin on connector 1 ?
01-12-2010 02:50 AM - edited 01-12-2010 02:57 AM
In the link you attached, the pdf named "SCB-68 M Series conn 1.pdf" is for the other M series card which use 2 connectors like 6229 & 6224. For the 6225 & 6255 card you have a psecial pdf for it (SCB-68 6225 & 6255 conn 1.pdf) because these cards have 80 analog inputs. So, you can see that regarding the other M series cards the connector 0 is the same, the difference is only for the last 64 inputs on the connector 1.
For information, you can access these pinouts of your card from the NI-DAQmx Device Terminals help file that is installed with DAQmx. A quick way to access this file with the exact pinout you need is from Measurement and Automation Explorer (MAX). In MAX under Devices and Interfaces, right-click on your device and select Device Pinouts. This will open the help document, as well as go directly to the pinout diagrams for that particular device.
01-18-2010 05:08 PM
Thanks again for all this information.