5B46 thermocouple module testing

I am trying to test my 5B46 Thermocouple modules using an external temperature calibration tester and my output voltage is 6.5v . No changes are seen in output voltage regardless of thermocouple input. Same result on other modules as well. I am using 5.0v dc supply, common tied to both power and I/O common. I also have the enabled tied to power common so output is enabled. Is there something I am missing in this test setup?