SCXI 1300 module

[STUDEN]

Hai,

I am using SCXI 1300 module to read temperature values using J type thermocouple. When I am measuring the room temperature, it is showing wrong value. (If the daisy chain index is changed from 0 to 7 , the room temperature differs) I need to measure the temperature of a hot plate. I am using 10 thermocouples. Please anyone help me.

Thank You.

[hoffiz]

Hi,

My first suggestion is to make sure you are connecting the thermocouple like we specified in page 7 of the SCXI-1300/1301 Guide and Specifications.  My second suggestion is to make sure the scxi-1300 is selected as the accessory of your module, since this card has a built in CJC; you need to configure your system to know that. The name of the channel for the CJC is called cjtemp in the case you want to make mueasurment directly to it.

This is a discussion forum of another customer that had a similar issue, take a look at it and follow the conversation; this is a good reference on how a misplace jumper may make the card read the incorrect voltages. Voltage Measuring error in LabVIEW with scxi-1100/1300. Another very good reference is the article in DevZone How to Use Thermocouples with an SCXI-1102 Module

Where are you reading the voltages, test panel or LabVIEW?

I hope it helps

[STUDEN]

Dear Mr. Jaime,

I am using SCXI 1102 with SCXI 1300 as accessory. I have given the connection asper the manual. I have reconfigured and reinstalled the SCXI 1000 many times in MAX.Iam reading the the temperature values in LabVIEW.

First I want to confirm it reading the room temperature. It was reading correctly. When I connected 5 thermocouples to read the temperature of the metal plate (not at heated cnd), I got the values of -325 deg C for all the TC readings in LabVIEW. I have enclosed the screen view of one TC value for your kind reference.

Please help me in this regard.

Thanks.

[hoffiz]

Hi,

Here are some questions I have, what happens if you read the temperature from just one thermocouple, attached to the metal plate? What happens if you try the read the room temperature when 5 thermocouples are connected but you read them one by one?

On suggestion is to make sure you don’t have the thermocouple touching the metal plate, since this can create ground loops and give bad readings.

Taking Thermocouple Temperature Measurements. For further references.

Let me know if it helps

[STUDEN]

Dear Mr.Jaime,

My aim is to measure the temp of heated metal plate at five different places. For that, to check whether it is working correctly, I measured room temp. using only one TC. It was reading correctly. So as per my requirement, I connected five TCs to SCXI module,  it was reading - 325 deg C(constant ). So to verify again with the room temp., I used only one TC to measure the room temp. again, I could not read the room temp. correctly as before. In the file I have attched, I have shown only room temp. measurement, showing -320/-325 deg C.

What could be the problem?

Thanks.

[hoffiz]

Hi,

Again, remember not to place the thermocouple directly on the metal plate. Like I told before there should be electrical isolation between the thermocouple and the metal plate.

Another test we can do to determine that all the channels in the SCXI-1300 are reading properly is to read the “room temperature” in each one of them; one by one. Every time you change your connections make sure you are changing the channel in your DAQ Assistant.

After you have finished this test I will start reading “room temperature” increasing the number of channels by one.

Waiting for your

[STUDEN]

Dear Jaime,

I have tried a lot. But nothing works. I need to measure the surface temperature of the metal plate. I have reconfigured and reinstalled the module many times. So now I am looking for any amplifying circuit. Can AD594 used instead of SCXI 1300 module? That is, a seperate amplifying/filtering/conditioning circuit shall be devised using AD594. Is it possible?

Thanks.

[hoffiz]

Hi,

The SCXI-1102 should have the conditioning needed for thermocouple readings. Why do you think the AD594 will help? My suggestion of reading room temperature on channel at a time was intended to search for a defective channel in the SCXI-1300 or the 1102.  

Let’s take a step back and try again what I told you before: let’s read from channel #1 then channel #1 and #2 then #1, #2 and #3 and so on; please document the result of this test. I will also like to try using other channels on your 1102 since you have 32 thermocouple channels, also change slots on you SCXI chassis.