You are referring to the DTEMP configuration of the SCXI-1303. The DTEMP configuration is not supported anymore in the device drivers - and there is technically no compelling advantage to using the DTEMP configuration over MTEMP anymore. To use the SCXI-1303's CJC with the SCXI-1600, all you need to do is set the jumper on the SCXI-1303 (if applicable) to MTEMP. Then, you will need to configure the SCXI-1100 in MAX to have a SCXI-1303 terminal block. When you create your thermocouple channel with the DAQ assistant, make sure that you select "Built-in" for the CJC, and the CJC temperature will automatically be scanned and applied to the readings.
-Logan K