scxi 1112 can not acquire correct data at high temperature(higher than 700C)

[gq]

A scxi-1112 module in scxi-1001 chassis is used to acquire oven Temperature. Software is LabView 8.5. when oven is ramping higher than 700C, the module gets wrong data, the data acquisition VI shows random values around 700C.It seems the scxi-1112 module "reaches" its maximum setting, which actually is 1000C. Can Anybody explain what's happening to me? Thanks.

[Steve_B]

Hi gq,

If you have a Voltage Task configured with a custom scale there are a few possibilities that could be the issue. The Signal Input Range could be limiting your measurement because the Max/Min value is set too high/low. A scale can be limiting your measurement if you are using a table scale that is not defined for the entire range of the sensor. The table scale will only return the maximum defined value for a measurement that is beyond its range. You can use a voltage measurement to be sure that your voltage is increasing beyond the maximum threshold you are experiencing. Let me know if I have made an incorrect assumption about your configuration and you have set up another task such as temperature and how it is configured.

[gq]

Hi Steve,

Thanks for your reply. I configured the SCXI-1112 by DAQ Assistance. There are two kinds of analog input in the task: Thermocouple(range: 0C-1000C, K-type) and Voltage (range:-5VDC--5VDC). Do these voltage input affect thermocouple reading?

Thanks.

[dansch]

Hi gq,

Could you please provide a screenshot of the way you are configuring the task, as well as what the data looks like that you are seeing when it behaves incorrectly? If you just perform a voltage reading (instead of a temperature task), what values are returned, and does it show the same behavior of reaching a certain voltage and not ramping any higher? Also, how do you have your thermocouple attached to your oven; is there any possibility that the connection is conducting at that temperature? Also, regarding the use of different measurements in the task, are you using different modules in your system or are the measurements being done on the same 1112 module? Additionally, have you tried other channels and received the same problem? I look forward to reading your response.

Regards,