Siemens Simatic S7-400 - Page 44

Receiving with the 3964(R) Procedure (part 2)
The 󹪝gure below illustrates receiving with the 3964(R) procedure.
Send DLE
CDT
expired ?
Send NAK
No
No
Yes
Yes
DLE doubling
No
Yes
No
Yes
No
Initialization
conflict, own priority low
Yes
Yes
No
No
no errors, not
DLE
Add character delay time
Character
received ?
Note NAK
faulty, DLE combination
not permitted
Yes
No
with BCC
3964(R) ?
Add character delay time
BCC received ?
BCC correct ?
NAK noted ?
Character delay time
expired ?
Send NAK
Send NAK
W > W max. ?
Add repeat time
STX received
Repeat time
expired ?
Receiving with procedure 3964(R) (part 2)
Z
D LE D LE
2
D LE E T X
G
5
G
G
G
3
G
Figure 2-18 Flow diagram of receiving with the 3964(R) procedure (part 2)
Basic Principles of Serial Data Transmission
2.5 Data Transmission with the 3964(R) Procedure
Point-to-point connection CP 440 Installation and Parameter Assignment
44 Equipment Manual, 03/2022, A5E00057742-AE