SCXI detection - input errors

[JDog]

I am having problems with a simple SCXI system that I am trying to install a simple SCXI system to input a voltage from an electrometer and output a voltage to a rotator. My problem is in detection of the chassis/reading correct voltage from the inputs. I am using a pci-1200 DAQ card from NI, an SCXI-1000, 1102 with 1300 terminal for the input, and a 1124 with 1325 for the output.

In troubleshooting, I have found the following 2 situations:

When I connect the SCXI 1102 module to the DAQ card with the 1124 module also in the chassis, the Ni-DAQ program cannot verify the chassis. This is regardless of which slot either module is plugged in.

When the 1102 module is the only module in the chassis, Ni-DAQ does verify the chassis, and the voltage read is correct (I hooked up a battery to verify this along with a thermocouple).

When the 1124 is installed alone, the output works correctly as well.

When both the 1124 and 1102 are installed, and the 1124 is connected to the DAQ card, Ni-DAQ verifies the chassis, and the output signal from the 1124 is correct. The problem is that the input through the 1102 module no longer gives the correct value...it isn't even close.

Any suggestions would be very helpful.

[Logan_K]

I am fairly certain that there is a problem with the SCXI-1102; if you have another SCXI-1102 that you could try, then you could verify that it is the 1102 and not some other part of the system. With the SCXI-1102 and the SCXI-1124 in the same chassis, the 1102 must be the cabled module because the SCXI-1124 doesn't have the ability to route analog signals back to the DAQ device, which is why you were getting incorrect readings when the 1124 was the connected device.

Logan Kunitz
Product Support Engineer
National Instruments

[JDog]

Thanks.

I will try to find someone with another 1102 module and see if it works.