Table 13.4.6A Number Of Transmit Data Bytes Setting - Fujitsu F2MC-16LX MB90580 Series Hardware Manual

(3) Slave address field
This field outputs the address of the other unit with which the master is to communicate and is consisted of
12 bits of slave address with MSB transmitting first, parity bit and acknowledge bit.
After a 12-bit slave address has been transmitted, a parity bit is output to ensure that the slave address is
not received by mistake. Then the master unit detects an acknowledge signal from slave unit to confirm its
existence on the IEBus. After the detection of acknowledge signal, the master unit starts outputting the
control field. However in multiaddress communication mode, the master starts outputting the control field
without detecting the acknowledge bit.
In the slave side, when it detects that the slave address has coincided with its own unit address, and the
parity bit in both master address field and slave address field are even, it outputs an acknowledge signal.
However, if parity bit is odd, the slave unit judges that either master address or slave address has been
received incorrectly, and then acknowledge signal is not returned. At this moment, the master unit enters
the standby (monitor) status, and communication ends.
In multiaddress communication mode, the slave address is used to identify whether it is group
multiaddress or broadcasting communication as follows:
When slave address is FFFH: Broadcasting communication
When slave address is not FFFH: Group multiaddress communication
Note:The group number for group multiaddress communication is identified by the higher
4 bits of the slave address.
(4) Control field
This field is used to control the type of following data field and direction of data transfer between master
and slave. This field is consisted of 4 bits of control bit with MSB transmitting first, parity bit and
acknowledge bit.
If even parity is checked and the slave can execute the function requested by the master, the slave returns
an acknowledge signal and then proceeds to the telegraph length field. Even though the parity is even, but
if the slave unit cannot execute the function requested by the master, or if the parity is odd, the slave unit
does not output the acknowledge signal and returns to the standby (monitor) status.
After the master confirms the return of acknowledge signal, it proceeds to the telegraph length field. If the
master cannot receive the acknowledge signal, it enters the standby status, and communication ends. In
multiaddress communication mode, the master unit does not detect the acknowledge signal, but proceeds
to the telegraph length field.
(5) Telegraph length field
This field is used to indicate the number of bytes of transmit data from the transmitter to receiver. This field
is consisted of 8 bits of telegraph length with MSB transmitting first, parity bit and acknowledge bit. Table
13.4.6a shows the relationship between the telegraph length field and the number of transmit data bytes.
Note:According to the communication mode being set, if the number of transmit data
bytes set in telegraph length field is greater than the maximum number of transmit
data bytes per frame, then communication with multi-frame is performed. In this
MB90580 Series

Table 13.4.6a Number of transmit data bytes setting

Telegraph length bits
(HEX)
01H
02H
..
..
FFH
00H
13.4 IEBus Communication Protocol
Number of transmit data bytes
1 byte
2 bytes
..
..
255 bytes
256 bytes
Chapter 13: IE Bus 167