What is the differences between "ble_nus" and "ble_nus_c"

[purgoufr]

In "ble_nus_c" file we can get nus_data with "ble_nus_c_evt_handler" function. We can do the same with "nus_data_handler" in "ble_nus" file. So why are there two separate ble_nus files? Also on a device I have defined as peripheral (sdk8.0.0 s110) I get nus_data using "nus_data_handler" function, I can not get nus_data using "ble_nus_c_evt_handler" function on a device I defined as central (sdk10.0.0 s130). I do not know why but I wonder Why are there two separate Nordic UART Service functions?

[Nguyen Hoan Hoang]

ble_nus_c is the Central mode. This mode is equivalent to the phone.
ble_nus is peripheral mode. This mode is the device.

You can have 2 nRF5 talking to each other where one is running ble_nus and other running ble_nus_c.

[purgoufr]

Can I use ble_nus("nus_data_handler") on central mode?

[Nguyen Hoan Hoang]

each of them has its own data handler. They are not the same. You can't mixed them. Please see the examples in the SDK how to use it.