How does 34921A without 34921T measure thermocouple?

Frequently Asked Questions (FAQs)

Summary

How to use external or fixed reference to measure thermocouple

Question

How does 34921A without 34921T measure thermocouple?

Answer

Whether or not customer has the 34921T, if he want to use and external reference, he must have an RTD or thermistor connected to one of the 34921A channels and set that up as an external reference channel with the commands provided for that purpose.   But if customer uses an external “bath” , that is normally an accurately fixed temperature reference and customer would not have to measure it.   In this case,customer would set the external reference source to fixed and use the command to set the bath temperature as the reference.

TSIL is only used with the 34921T to communicate the 34921T internal reference temperature to the 34980A.   That line is not brought out for a customer connection as you can see from the 34921T terminal labels.   There is an temperature measurement IC on the 34921T PCA that has a serial bit stream output for the reference temperature.