Error Messages In The "Receive" Coordination Byte - Siemens SIMATIC S5 Series Manual

S5-95U, Second Serial Interface

Error messages in the "receive" coordination byte

In a receive request, various errors may occur, which are assigned different priorities by the
computer link. The KBE always contains the error which has the highest priority in the last receive
attempt. In Table 3-2, the highest priority has the value 0 and the lowest is assigned the value 6.
Table 3-2 Error Messages in the "Receive" Coordination Byte
Assignment
03 Parity error
H
05 Frame with length 0
H
07 Input buffer full
H
09 Too many frames received
H
(more than 100 frames)
0B Frame longer than receive mailbox
H
DLE was not duplicated or no ETX
0D
H
after DLE*
0F Receive mailbox not available
H
11 STX error; handshaking did not start
H
with STX **
13 DT character delay time error
H
15 BWT block wait time error
H
17 Check sum error
H
1B Break
H
*
DLE and ETX are control characters for connection buildup and cleardown (DLE = Data Link Escape, ETX = End of
Text). The procedure automatically duplicates this data item to make sure that a data item having the same code as a
control character (DLE in this case), is recognized as data by the procedure.
The control character sequence DLE - ETX is fixed to ensure a proper connection cleardown.
** STX is the control character for extablishing the link with the other node (STX = Start of Text).
The position of the coordination bytes is to be parameterized in DB1 ( Section 3.4).
EWA 4NEB 812 6095-02
Computer Link with 3964(R) Transmission Protocol
Meaning Priority Response
5
Data rejected
6
2
2 Data valid but the following
frames have been rejected
0
Data rejected
3
0
3
4
2
5
1
3-9