Extech 4 channel data logging digital thermometer extech sdl200 the extech sdl200 4 channel data logging thermometer records data on an sd card in microsoft excel reg format for easy transfer to a pc for analysis the sdl200 is able to log 4 channels with 6 thermocouple types j k e t r s and 2 channels with rtd pt100 omega probes displays t1 t2 t3 t4 or differential t1 t2 reading the user can manually store 99 readings or set the logger to automatically store up to 20m sa