NI 9213 Stops updating temperature values

[Controls_Engineer]

I have a CRIO Chassis NI 9074. It has a NI 9213 in the first slot followed by a NI 9205, NI 9264 and NI 9477. This setup is used to read 16 thermocouples, few flow meters, control few blowers and pumps and turn on/off heaters.

When I am using the heater to heat the system, the NI 9213 suddenly (after reading for a few minutes)stops updating the temperature values and is stuck to the old value. The time and temperature at which it gets stuck is different every time. Even if I disconnect a thermocouple it does not detect the open thermocouple. At this time all the analog input values are being updated and the analog outputs and digital outputs are also being updated. I have to reboot the CRIO chassis or cycle power to the chassis to make start reading the temperatures again.

Can you please suggest what is causing the NI 9213 to stop reading and show its old value?

Thanks.

[Christian Mergl]

Hi,

Are you doing ScanInferface or FPGA Programming?

Did you check, and if so, how did you check it, if the loop where the 9213 will be read is still running when you don't get readings anymore?

Christian

[Controls_Engineer]

I am using scan interface. The same loop is reading the analog input values also and these values are being updated. So I am assuming that the loop is still running. Also, if I put a probe on one of the TCs, it shows the value. If the loop is not running it shows "Not Executed".

[Christian Mergl]

You said: "... if I put a probe on one of the TCs.."

Are you talking about a probe on the variable in LabVIEW?

Christian

[Controls_Engineer]

Yes, Probe in LabVIEW

[Christian Mergl]

Then it would be great if you could post your code here. Since the value is present on the variable, the module is reading and all the stuff from the scaninterface works. There must be something wrong from between the variable and the part where you don't see any updates after a certain time.

Christian

[nausfaratu]

Is there any update about this issue. I am having exactly the same problem with an NI 9213 too and can't be able to solve it yet.

[Controls_Engineer]

Actually this was caused due to a grounding problem. There was a heater used in the system which was not grounded properly. As soon as the heater was turned on, the thermocouple signals were getting affected. After we grounded the heater with the rest of the system the problem was solved.

I suggest that you please check if there are any round loops in your system.

Thanks.

[nausfaratu]

Thanks! a lot body.

That was my problem, bad ground. My system have the heaters insulated with ceramic from the chassis, and obiously that avoid the ground. I put gound in all of them and voala, problem solved.

Thanks again.