Lenze I/O system 1000 System Manual - Manual (Page 736)

Appendix
Serial process interfacing
Principle of backplane bus communication
15
l
736 EDSIO1000 EN 7.0
Receive data
During reception, the data received are entered automatically in the input area of the
higher−level system by the I/O compound module. Depending on the length of the data
received, the telegram is transmitted to the higher−level system in one or several
fragments.
Reception without fragmentation:
Higher−level system EPM−S640/EPM−S650 Description
Byte Function Byte Function
0 Information byte Bits 3...0:
8
h
= idle state, no data available.
9
h
= data are transmitted in a
fragmented manner.
A
h
= data are transmitted without
fragmentation.
Bits 7...4:
Reserved for transmission
1 Telegram
information byte 00
h
= the telegram does not contain any
additional offset data.
04
h
= the telegram contains additional
offset data, which are placed behind the
length as word. Via the offset data, the
position of the user data in the input area
is determined.
2 High byte length Length of the user data in bytes plus 2
bytes for RetVal.
3 Low byte length
[4] High byte offset If the telegram information byte has the
value 04
h
, an offset is entered
additionally. Otherwise there is no offset
in the telegram.
[5] Low byte offset
6 RetVal high byte 0517
h
= invalid length
(length = 0 or length > 1024)
080A
h
= a free receive buffer is not
available.
080C
h
= defective character received
(character frame error or parity error).
7 RetVal low byte
8 ... n−1 User data User data received; n = number of the
bytes assigned in the address range (IO
size)
¬
0 Acknowledgement ® 0 After having processed the data in your
higher−level system, you have to
acknowledge the reception to the I/O
compound module. Only then you can
provide these new received data.
Bits 3...0:
Reserved for transmission.
Bits 7...4:
8
h
: acknowledgement, idle state
A
h
: acknowledgement, input area free for
new data.
B
h
: command, execute a reset on the I/O
compound module.