install CPC Secondary - UART (USART) or CPC Secondary - SPI (USART) component depending on your CPC interface to the host processor. This will automatically install the CPC Core and CPC SECURITY components as well.
install as well IO Stream: CPC and modify its configuration to increase the transmit buffer size to 1024 at least so that the command responses won't get truncated. Remark that 1024 is not large enough to get the full "help" command response in Railtest application.
open sl_cli_config_inst0.h in the config directory of your project and modify line 110 as:
#define SL_CLI_INST0_IOSTREAM_HANDLE sl_iostream_cpc_handle
#if defined(SL_CATALOG_CPC_SECONDARY_PRESENT)
#include "sl_cpc_drv_secondary_uart_usart_vcom_config.h"
#define VCOM_RX_PORT SL_CPC_DRV_UART_CPC_RX_PORT
#define VCOM_RX_PIN SL_CPC_DRV_UART_CPC_RX_PIN
#define VCOM_TX_PORT SL_CPC_DRV_UART_CPC_TX_PORT
#define VCOM_TX_PIN SL_CPC_DRV_UART_CPC_TX_PIN
#endif
#if defined(SL_CATALOG_CPC_SECONDARY_PRESENT)
#include "sl_cpc_drv_secondary_spi_usart_exp_config.h"
#define VCOM_RX_PORT SL_CPC_DRV_SPI_EXP_RX_PORT
#define VCOM_RX_PIN SL_CPC_DRV_SPI_EXP_RX_PIN
#define VCOM_TX_PORT SL_CPC_DRV_SPI_EXP_TX_PORT
#define VCOM_TX_PIN SL_CPC_DRV_SPI_EXP_TX_PIN
#endif