Does ack needed for using Nordic UART service?

Question

My Windows app sends command though Nordic UART service to nrf52832 device. Does nrf52832 need to send ACK to let Windows App knows it has received command?

Marte Myrvold · Answer

Hi, 
 What do you mean by your Windows app? Is this an app you have made yourself, or do you mean something provided by Nordic? 
 If you are talking about ACK then this is handled by the link layer and is always enabled. The nRF52833 will not send an ACK packet, but the transmit sequence number (SN) and next expected sequence number (NESN) bits are used in each packet for ACK, so the Windows app will know whether the packet was received or not by comparing the NESN of the next packet it received from nRF52833 after sending the NUS command with the SN. 
 However, if you instead mean whether the nRF52833 must send a response to the command, then no. If you send a NUS write request then the device should send a write response back, but it does not send a response for a NUS command. You can test this out yourself by looking at a sniffer log. There you will also see SN and NESN:

Best regards, 
 Marte

Does ack needed for using Nordic UART service?

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