YASKAWA CP 040 RS422/485 Manual page 44

Deployment
Principal communication via back plane bus > Sending data
Acknowledgement Status
Principle of communica-
tion with fragmentation
Sequence
Calculating the number of
fragments
Write 1. telegram (Header)
Control-Byte
Telegram-Info-Byte
44
Bit 3...0 Reserved for receipt
Bit 7...4 n 8h: Acknowledgement: Idle state
n Ah: Acknowledgement: Data received without fragmentation
n Ch: Status: Reset was executed on the CP
n Dh: Status: The entered length is not valid
n Eh: Status: Error in CP communication
–
With the fragmented communication the number of user data and a part of the user data
are already transferred with the 1. telegram (header), followed by the fragment telegrams.
The CP responds every telegram with an acknowledgement, by copying bit 3...0 of byte 0
of the output area to bit 7...4 of byte 0 of the input area or sending back a status message
via this byte.
Write 1. telegram
n
n Write fragments
n Write last fragment
Host system
Byte Function
0 Control-Byte
1 Telegram-Info-Byte
2 Length high byte
3 Length low byte
4...n-1 User data byte
0 ...n-5
with n = number of used bytes in the address area (IO-Size)
Bit 3...0 n 8h: Idle state - no data available
n 9h: Start transfer with fragmentation
n Ah: Transfer last fragment
n Bh: Execute a reset on the CP
Bit 7...4 Reserved for receipt
00h (fix) when data are sent.
there is no response of the other station
u
t
VIPA System SLIO
CP
Byte Function
0 Acknowledgement / Status
HB300 | CP | 040-1CA00 | en | 18-28