Login (L) command


(see command description format info here)

Function:Authenticates the network host and opens the network programming session
Can be issued through:Network (broadcasts ignored*)
Command format:Lpp...p, where pp...p is the login password, 0-8 characters long
Possible replies:A, R, D
First introduced:Earlier than "baseline" V3.14/V3.51
See also:Authentication, Programming priorities, Error mode


Login command is used to authenticate the network host, which is a necessary step to perform before attempting to execute certain commands over the network (such as Set Setting (S) .  Check the "L" column of the command table at commands, messages, and replies to find out which commands require prior authentication.

Login password to supply in the Login command body is defined by the Password (PW) setting . Note, that to execute commands that require prior login you need to use the Login command even when the password is not set (i.e. it is <NULL>).

OK (A) reply code is returned if login is accepted by the DS. Rejected (R) reply code is returned if the DS is in the serial programming mode or a higher-priority programming session is already in progress (see programming priorities for details). Denied (D) reply code is returned if incorrect password is supplied.

Login command is said to open a programming session. For more information on programming sessions see authentication .

The DS memorizes the IP-address of the network host from which the Login command is sent. If subsequent commands (that require login) are sent from a different IP-address then these commands are replied to with the Denied (D) reply code .

Login password is not verified when the DS is running in the error mode . Login command should still be used as usual but it is not necessary to supply any password, leaving the pp...p field blank in this situation is OK.

* Without prior selection using Select In Broadcast Mode (W) command .