ANT+ FEC page 51 scanning from external device

Question

I am trying to “spy on” two ANT+ devices talking to each other: 
 
 The first device is a bike trainer running the ANT+ FEC profile 
 The second device is a computer (running Zwift and sending commands to the trainer) 
 
 My goal is to receive the ANT+ messages coming from the computer on a nRF52832 (and especially page 51 of the FEC profile). 
 I managed so far only to receive the bike trainer ANT+ messages, but not the messages sent from the computer. 
 What should I change in my configuration ? 
 (The bike sends pages 16 and 25 – speed and power- , and the computer should be sending acknowledged data page 51 – simulated slope -). 
 I am using a continuous scanner to listen from the nRF5232 configured as follows: 
 ant_channel_config_t channel_config =
 {
 .channel_number = 0x00,
 .channel_type = CHANNEL_TYPE_SLAVE,
 .ext_assign = 0x00,
 .rf_freq = 0x39,
 .transmission_type = WILDCARD_TRANSMISSION_TYPE,
 .device_type = FEC_DEVICE_TYPE,
 .device_number = 0x00, // Wildcard
 .channel_period = 0x00, // Not used, since this is going to be scanning
 .network_number = ANTPLUS_NETWORK_NUMBER,
 };

vincent.golle · Answer

The problem is now solved, by the use of the function sd_ant_rx_scan_mode_start instead of sd_ant_channel_open. 
 The code to activate scanning of both masters and slaves is the following: 
 
/**@brief initialize application
 */
static void continuous_scan_init()
{
 uint32_t err_code;

 // Set library config to report RSSI and Device ID
 err_code = sd_ant_lib_config_set(
 ANT_LIB_CONFIG_MESG_OUT_INC_RSSI | ANT_LIB_CONFIG_MESG_OUT_INC_DEVICE_ID);
 APP_ERROR_CHECK(err_code);

 // Configure channel 0 for scanning mode
 ant_channel_config_t channel_config =
 {
 .channel_number = CT_CHANNEL_NUMBER,
 .channel_type = CHANNEL_TYPE_SLAVE,
 .ext_assign = 0x00,
 .rf_freq = FEC_ANTPLUS_RF_FREQ,
 .transmission_type = 0x05u,
 .device_type = FEC_DEVICE_TYPE,
 .device_number = TACX_DEVICE_NUMBER,
 .channel_period = FEC_MSG_PERIOD, // Not used, since this is going to be scanning
 .network_number = ANTPLUS_NETWORK_NUMBER,
 };

 err_code = ant_channel_init(&channel_config);
 APP_ERROR_CHECK(err_code);

 // Activate message reception from the slave as well
 // This function starts receive scanning mode feature. Channel 0 must be assigned. All other channels must be closed.
 err_code = sd_ant_rx_scan_mode_start(0);
 APP_ERROR_CHECK(err_code);

}