J Type Thermocouple to Analog Input Card

[Charles4th]

Is it possible to wire a J type Thermocouple directly to a Allan Bradley Analog input card, specifically a 1769-IF4 card, and scale the reading to display the temperature on an HMI.

Thanks

 

[Nova5]

No, thermocouples operate in millivolts. Analog in Volts or mA. also Thermocouple connections need to be of the same differential materials so the reading is correct. A basic analog card doesn't do that. You either need a Thermocouple card or transducer type device. Transducers are pretty small. I use some that are basically the 25% larger than a good ol ZipDisk.

 

[OkiePC]

No, the thermocouple is a passive device that returns a millivolt signal. You need a signal conditioner and that is my preferred way to connect thermocouples to A/B PLCs. Thermocouple PLC cards are more expensive and sometimes bringing the thermocouple wiring all the way back to the PLC subjects it to induced noise that is much less of a problem than it is with 4 to 20mA signals which is what your IF4 card requires (although it could also accept 0 to 10vdc, milliamps is my preference).

One example of a suitable conditioner:

https://www.automationdirect.com/ad...uple_input)/connection_head_mount/xth-0500f-j

 

[lfe]

In addition, the millivolt-temperature relationship is not linear, but follows a characteristic curve of the type of thermocouple used.

Therefore, it is essential to use a specific input or converter for the type of thermocouple used.

It must also incorporate ambient temperature compensation, since a thermocouple does not measure an absolute temperature but the difference between the cold junction and the hot junction

 

[L33er]

you need 1769-IT6

 

[doctord]

My preference is to use a TC with a connection head that contains a signal converter to convert to mA signal. If there is room for this setup on the machine. This way the signal is converted to mA right at the probe so less likely to have interference. Nice neat installation and you can go to the analog input card directly from the connection head.

 

[Charles4th]

Thanks to all who replied!

I am looking at using the following Part No. 931H-T1C1D-DC, to condition the signal into the 1769-IF4 card.

I am also using the card to monitor a 4-20mA signal from an ultrasonic distance measuring sensor which is why I am using the 1769-IF4 card and not the straight up 1769-IT6 Thermocouple input module.

Best regards

 

[mylespetro]

Thanks to all who replied!

I am looking at using the following Part No. 931H-T1C1D-DC, to condition the signal into the 1769-IF4 card.

I am also using the card to monitor a 4-20mA signal from an ultrasonic distance measuring sensor which is why I am using the 1769-IF4 card and not the straight up 1769-IT6 Thermocouple input module.

Best regards

Looks like that should work to me, someone else might chime in with a reason why it wouldn't, but I can't see anything wrong with it. I'm assuming there's an existing 24VDC power supply that you can use?

 

[Nova5]

Thanks to all who replied!

I am looking at using the following Part No. 931H-T1C1D-DC, to condition the signal into the 1769-IF4 card.

I am also using the card to monitor a 4-20mA signal from an ultrasonic distance measuring sensor which is why I am using the 1769-IF4 card and not the straight up 1769-IT6 Thermocouple input module.

Best regards

https://www.instrumart.com/products/44081/define-instruments-javelin-isolated-transmitter
I use these to perform the same job. Highly flexible. Just need the bridge key/USB adapter to connect to them and program them. You can set the fail mode as high or low. It can be used for Thermocouples, RTDs, as a 4-20 isolator... if the field device is a 4wire and generates its own 24v power, but you also have everything generally powered from house/panel power. This can sit between them and isolate the two 24v supplies from each other, while passing on the 4-20 signal state.