Issue link: https://read.uberflip.com/i/1428383
LoRaWAN 1.0.3 Specification ©2018 LoRa™ Alliance Page 23 of 72 The authors reserve the right to change specifications without notice. CID Command Transmitted by Short Description End- device Gateway 0x0B to 0x0C RFU 0x0D DeviceTimeReq x Used by an end-device to request the current date and time 0x0D DeviceTimeAns x Sent by the network, answer to the DeviceTimeReq request 0X0E to 0x7F RFU 0x80 to 0xFF Proprietary x x Reserved for proprietary network command extensions Table 5: MAC commands 623 Note: The length of a MAC command is not explicitly given and must be 624 implicitly known by the MAC implementation. Therefore unknown MAC 625 commands cannot be skipped and the first unknown MAC command 626 terminates the processing of the MAC command sequence. It is 627 therefore advisable to order MAC commands according to the version 628 of the LoRaWAN specification which has introduced a MAC command 629 for the first time. This way all MAC commands up to the version of the 630 LoRaWAN specification implemented can be processed even in the 631 presence of MAC commands specified only in a version of the 632 LoRaWAN specification newer than that implemented. 633 634 Note: Any values adjusted by the network server (e.g., RX2, new or 635 adjusted channels definitions) remain only valid until the next join of the 636 end-device. Therefore after each successful join procedure the end- 637 device uses the default parameters again and it is up to the network 638 server to re-adjust the values again as needed. 639 5.1 Link Check commands (LinkCheckReq, LinkCheckAns) 640 641 With the LinkCheckReq command, an end-device MAY validate its connectivity with the 642 network. The command has no payload. 643 When a LinkCheckReq is received by the network server via one or multiple gateways, it 644 responds with a LinkCheckAns command. 645 646 Size (bytes) 1 1 LinkCheckAns Payload Margin GwCnt The demodulation margin (Margin) is an 8-bit unsigned integer in the range of 0..254 647 indicating the link margin in dB of the last successfully received LinkCheckReq command. A 648 value of "0" means that the frame was received at the demodulation floor (0 dB or no margin) 649 while a value of "20", for example, means that the frame reached the gateway 20 dB above 650 the demodulation floor. Value "255" is reserved. 651 The gateway count (GwCnt) is the number of gateways that successfully received the last 652 LinkCheckReq command. 653