Thank you for the advice. I was trying to check the drive current from the SDL 822 for the TEC. To do that I switched on the SDL and then tried to check the current and voltage from the respective pins for TEC with multimeter. It shows few mA and few mV. In the manual I checked that if there is no thermistor connected then TEC drive voltage limit will be set to zero. How can I check the current then without connecting the thermistor? Any suggestion? Thanks in advance!