Telnet TCP Programming [V3.50 and Above]

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"Telnet" TCP programming is the new programming method that is supported by firmware V3.50 or higher. Telnet programming is called so because it is effected through a TCP connection to port 23 of the DS (This is a standard telnet port). Such connection can be established regardless of whether current Transport Protocol (TP) [setting/parameter] is 0(UDP) or 1(TCP).

 

Several TCP connections to port 23 can be established at the same time but only one of them will be at "logged in" state at any given time i.e. have a programming session in progress (see authentication and programming priorities).

 

Note, that port 23 cannot be used for programming if this port is assigned to be the data port (i.e Port Number (PN)= 23). In this case all TCP connections to port 23 will be interpreted as data connections, thus rendering "telnet" programming impossible. If the Port Number is set to any port other than 23, a TCP connection to port 23 will be interpreted as a programming connection. 

 

All telnet commands and replies use the following format:

 

STX

Command/reply

CR

 

Thus, telnet commands and replies have the same format as those used in serial programming. STX (ASCII code 2) and CR (ASCII code 13) characters provide necessary encapsulation. All data before the STX and after the CR is ignored. Command/reply field contents has been explained in programming.

 

note_further-wt

The replies from the DS will include an additional LF character trailing the CR at the end of the reply, just to improve readability on most terminal software. You don't have to send an LF when you send commands to the DS.