User's Manual

RS232-Transponder Reader
(SECS1-Protocol), Release 0.3 Draft Page 37 of 91
2000-09-29
ID: ID000093
Upper Device-ID
Lower Device-ID
Direction reader to host: 0x81xx *
Direction Host to equipment (HERMOS SECS-1 Reader): 0x01xx *
* … the serial number is on a sticker on the cap of each reader
The W-Bit is used to indicate that the sender of a primary message expects a reply.
A value of one in the W-bit means that a reply is expected.
The message ID identifies the format and contents of the message being sent.
A primary message is defined as any odd numbered message.
A secondary message is defined as even any numbered message.
The end bit is used to determine if a block is the last block of message. A value of
one means that the block is the last block.
A message sent as more than one block is called a multi-block message. A block
number of one is given to the first block, and the block number is incremented by
one for each subsequent block until the entire message is sent.
As all messages can ever be sent in one block, the block number always has the
value 1.
The system bytes in the header of each message for a given device ID must
satisfy the following requirements:
• The system bytes of a primary message has to be distinct from those of
all currently open transactions initiated from the same end of the
communications link.
• The system bytes of the reply message are required to be the same as
the system bytes of the corresponding primary message.
The system bytes are incremented for each primary message. Only the two lowest
bytes (byte 9 and 10 of the header) are incremented. For a primary message of the
reader, additionally byte 8 of the header is used for the reader action number.
The checksum is calculated as the numeric sum of the unsigned binary values of
all the bytes after the length byte and before the checksum in a single block.
R
Not used
0x01
serial number of the reader