Fujitsu F2MC-8FX Series User Manual page 84

1. Break
Break, which are in the header fields, are variable-length fields that indicate the start of a
new frame. They comprise 13 to 16 "0" bits (fixed value zero) min. The general frame
length is 13 bits.
2. Sync Byte
Sync byte, which follow on from breaks, are 10-bit fixed-length fields that synchronize the
master and the slaves. Sync byte configurations comprise 1 starter bit ("0"), 8 data bits, and
1 stop bit ("1").The 8-bit data bit has the fixed value "0x55" (which is expressed as
"0x01010101" in binary).If the slave receives the 0x55 in the synch byte send by the master
normally, the master and slave are synchronized.
3. ID field
The "ID field", which is the final header field and comes after the synchronous byte, is a
10-bit fixed-length field that specifies the frame type and objective. ID fields have values
from "0" to "63" (6 bits).This ID field is also used by the master to specify individual slaves.
Slaves judge what type of frame has been sent and if it was intended for them according to
the ID field sent by the master, and send responses to the master accordingly. Further, the ID
field has a 2-bit parity bit following the "0" to "63" (6 bits).This is bracketed by a 1-bit
starter bit and 1-bit stop bit in the same way as the synchronous byte, so overall the field is
10 bits in length.
4. Data field
The "data", which is in the response header, is a variable-length field that literally transfers
data. The data in the number of bytes that has been predetermined (1 to 8 bytes) is sent. As
there is a 1-bit start bit and 1-bit stop bit bracketing the 1-byte data in the same way as the
header synchronous byte, 1 byte of data is configured from 10 bits. Consequently, the total
data field length is "number of bytes x 10 bites".
5. Checksum field
The "checksum", which follows the data, is a 10-bit fixed-length field for checking data. The
data recipient checks whether there is an error in the data by comparing the data received
with the checksum. The checksum field length is also 10 bits: a start bit and a stop bit added
to the 8-bit checksum in the same way as the synchronous byte.
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