Hatteland Display 19 inch - JH 19T14 MMC - Manual (Page 8)

8
Serial Communication (SCOM) Interface
Communication Interface
IND100084-12
Data Rates
The unit is configured to transmit and receive data at 9600 bits/second (Serial mode)
Data Format Serial Mode
Data shall be transmitted with no parity, 8 data bits, one start bit and one stop bit.
Message Format
The basic message format shall be as follows:
Byte # 0 1 2 3 4 5 6 7, etc 8 or 7+DATA=END
ATTN ADDR CMD CMD CMD LEN IHCHK DATA IDCHK
The minimum message size is 7 bytes (0x07). The maximum message size is 82 bytes (0x52), consistent with the
EN61162-1 standard. Colors will be used throughout this manual to indicate byte positions. Every byte sent are viewed
in this document as HEX values and are based on standard characters in the ASCII table (0 to 255) to send or receive
messages in a human readable input/output. No further decoding or decrypting functionality is needed or required.
Every command sent and received should always end with a 0x00 (null byte terminator).
ATTN
Attention (ATTN)
This single byte is used to identify a start of message. 3 values are possible:
ATTN Description
0x07 Command, also known as ASCII BELL
0x06 Acknowledge, also known as ASCII ACK
0x15 Negative Acknowledge, also known as ASCII NAK
A device shall send a command using the 0x07 Attention Code. The unit will respond to the command with either an
ACK if the command completed successfully, or a NAK if the command failed.
NOTE: A complete HEX, ASCII, BIN and Character table overview are available in the APPENDIX chapter.
ADDR
Address (ADDR)
This single byte is used to specify a particular unit to receive a Command and to identify the unit responding (ACK
or NAK) to a Command. All units will support the broadcast address. The factory default adress is 0x00, while in this
manual illustrated throughout as 0xFF.
The Address field shall have the following values:
ADDR Description
0xFF Broadcast - Addressed to all units
0x00 to 0x0F Address of a specific unit, 0 to 15 (max 16 units)