How read data from multichanel ADC on STM32F1?

I guess it is not just a question Keil product, but I need your advice.
I am using STM32f1 with CubeMX and keil mdk5. in my project i have to read muti channel ADC value
ADC is in Scan conversion mode Enable, Number of conversion 2, Rank1 Channel Temperature sensor and Rank 2 Chane Vrefint.

while(1){ HAL_ADC_Start(&hadc);
while(HAL_ADC_PollForConversion(&hadc,0) != HAL_OK);
channel_1 = HAL_ADC_GetValue(&hadc); while(HAL_ADC_PollForConversion(&hadc,0) != HAL_OK);
channel_2 = HAL_ADC_GetValue(&hadc);
HAL_ADC_Stop(&hadc); }

Problem is booth call HAL_ADC_GetValue() retint value of Rank1 ti is voltage on Channel Temperature sensor. I can not figure out how to read value from next RANK 2

Thanks for help.