Command Control via the Network (continued)
2. Response code / Error code ("h" shows hexadecimal)
The connection ID is attached for the TCP#23's response / error codes are used. The connection ID is same as the sending command format.
(1) ACK reply : 06h + ××h | (××h : connection ID) |
(2)NAK reoly : 15h + ××h
(3)Error reply : 1Ch + 0000h + ××h
(4)Data reply : 1Dh + xxxxh + ××h
(5)Authentication error reply : 1Fh + 0400h + ××h
(6)Projector busy reply: 1Fh + ××××h + ××h
When the projector is too busy to receives the command ,the projector returens the error code.
In such a case, check the sending code and send the same command again.
Automatic Connection Break
The TCP connection will be automatically disconnected after there is no communication for 30 seconds after being established.
Authentication
The projector does not accept commands without authentication success when authentication is enabled. The projector uses a challenge response type authentication with an MD5 (Message Digest 5) algorithm. When the projector is using a LAN, a random 8 bytes will be returned if authentication is enabled. Bind this received 8 bytes and the authentication password and digest this data with the MD5 algorithm and add this in front of the commands to send.
Following is a sample if the authentication password is set to “password” and the random 8 bytes are “a572f60c”.
1)Select the projector.
2)Receive the random 8 bytes “a572f60c” from the projector.
3)Bind the random 8 bytes “a572f60c” and the authentication password “password” and it becomes “a572f60cpassword”.
4)Digest this bind “a572f60cpassword” with MD5 algorithm. It will be “e3d97429adffa11bce1f7275813d4bde”.
5)Add this “e3d97429adffa11bce1f7275813d4bde” in front of the commands and send the data.
Send “e3d97429adffa11bce1f7275813d4bde”+command.
6)When the sending data is correct, the command will be performed and the reply data will be returned. Otherwise, an authentication error will be returned.
NOTE • As for the transmission of the second or subsequent commands, the authentication data can be omitted when the same connection.
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