Receiving Data - YASKAWA CP 040 RS422/485 Manual

Deployment
Principal communication via back plane bus > Receiving data
Control-Byte
User data
Acknowledgement Status

4.3.2 Receiving data

Principle of communica-
tion without fragmentation
46
Host system
Byte Function
with n = number of used bytes in the address area (IO-Size)
Bit 3...0 n 8h: Idle state - no data available
n Ah: Transfer last fragment
n Bh: Execute a reset on the CP
Bit 7...4 Reserved for receipt
Enter here the user data for the serial communication.
Bit 3...0 Reserved for receipt
Bit 7...4 n 8h: Acknowledgement: Idle state
n Ah: Acknowledgement: Last fragment received
n Ch: Status: Reset was executed on the CP
Dh: Status: The entered length is not valid
n
n Eh: Status: Error in CP communication
–
When receiving data from the CP, the data are automatically transferred to the input area
of the host system.
Depending on the length of the received data, the telegram is transferred to the host
system as one fragment or with multiple fragments.
The fragmented transfer is started by copying bit 3 ... 0 of byte 0 of the input area to bit
7 ... 4 of byte 0 of the output area. Possible errors during the transfer may be found in
RetVal.
Host system
Byte Function
t
there is no response of the other station
u
VIPA System SLIO
CP
Byte Function
0 Acknowledgement / Status
CP
Byte Function
0 Info-Byte
1 Telegram-Info-Byte
2 Length high byte
3 Length low byte
[4] Offset high byte
[5] Offset low byte
6 RetVal high byte
7 RetVal low byte
HB300 | CP | 040-1CA00 | en | 18-28