Scaling of Analog Input on SCC-AI03

[Tunedport]

Hi,

I am working on a machine which uses a PCI-6036E going to a SC-2345 reading an analog input from a SCC-AI03. This system is running a custom VB6 application that reads and stores this value.

The system was running fine for about 4-5 years and suddenly would not read any values from the SCC. After performing some basic troubleshooting I determined that either the SC-2345 or the SCC-AI03 was bad. We purchased both components and I was able to determine that the SCC-AI03 was the problem.

Now, with the new SCC-AI03 installed, I am able to see the analog signal in the Test Panel but the value seems to be scaled wrong. When I measure the analog voltage with a DMM I see a value ranging from 0 to +3 vdc, when I view the signal in the Test Panel I see a voltage of -10 vdc to -7 vdc. The VB6 application is seeing the raw signal as well.

Ultimately I would like to scale the value so that 0 vdc = 0 psi and +3 vdc = 30 psi.

How do I perform scaling of this signal? Is the scaling stored in the SCC-AI03, the SC-2345, or the PC somewhere? I can not understand why the scaling was lost by swapping out the two pieces of hardware.

I want to try to avoid making any program (VB6) changes or performing any other software updates (NI drivers, MAX, etc...) because I don't want to cause any other problems by upgrading software. The system is currently using the Legacy drivers and I am hoping that the new components are still compatible.

Please Advise.

Thank You,

Bill

[ryan_d]

Hi Bill,

Is your signal source floating? If so, the measured voltage might rail to that range. Make sure that you're properly ground referencing your source. Pages 5 and 6 of the SCC-AI Series Isolated Analog Input Modules User Guide provides details on how you should do this. Please post back if you have any questions. Have a great day!