Hitachi CP-SX635W Service Manual page 63

Command Control via the Network (continued)
Decreasing the projector setting value (Decrement command)
(1) The PC sends the following decrement code to the projector.
Header + Command data ('05H' + '00H' + type (2 bytes) + '00H' + '00H')
(2) The projector decreases the setting value on the above setting code.
(3) The projector returns the response code '06H' to the PC.
When the projector cannot understand the received command
When the projector cannot understand the received command, the error code '15H'
is sent back to the PC.
Sometimes the projector cannot properly receive the command. In such a case,
the command is not executed and the error code '15H' is sent back to the PC. If
this error code is returned, send the same command again.
When the projector cannot execute the received command.
When the projector cannot execute the received command, the error code '1CH' +
'xxxxH' is sent back to the PC.
When the data length is greater than indicated by the data length code, the
projector ignore the excess data code. Conversely when the data length is shorter
than indicated by the data length code, an error code will be returned to the PC.
When authentication error occurred.
When authentication error occurred, the error code the '1FH' + '0400H' is sent
back to the PC.
NOTE • Operation cannot be guaranteed when the projector receives an
unde ned command or data.
• Provide an interval of at least 40ms between the response code and any other code.
• Commands are not accepted during warm-up.
[TCP #9715]
1. Protocol
Consist of header (1 byte) + data length (1 byte) + command data (13 bytes) +
check sum (1 bytes) + connection ID (1 byte).
2. Header
02, Fixed
3. Data Length
Network control commands byte length (0D, Fixed)
4. Command data
Network control commands that start with BE EF (13bytes).
5. Check Sum
This is the value to make zero on the addition of the lower 8 bits from the header
to the checksum.
6. Connection ID
Random value from 0 to 255 (This value is attached to the reply data).
Command Control via the Network (continued)
7. Reply Data
The connection ID (the data is same as the connection ID data on the sending
data format) is attached to the Network control commands reply data.
ACK reply: '06H' + 'xxH'
NAK reply: '15H' + 'xxH'
Error reply: '1CH' + 'xxxxH' + 'xxH'
Data reply: '1DH' + 'xxxxH' + 'xxH'
Projector busy reply: '1FH' + 'xxxxH' + 'xxH'
Authentication error reply: '1FH' + '0400H' + 'xxH'
('xxH' : connection ID)
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.