Basic Principles of Serial Data Transmission
2-33
Point-to-point connection CP 440 Installation and Parameter Assignment
A5E00057742-02
Sending with the 3964(R) Procedure
The figure below illustrates sending with the 3964(R) procedure.
Wait for DLE
acknowledg-
ment
Intention to
send
W = 1
3964
G
2
Send STX
3
Start T
ADT
Send block,
poss.
duplicate DLE
Send DLE,
ETX
Start T
ADT
Send BCC
Wait for DLE
acknowledg-
ment
G
DLE
Sending completed
T > T
ADT
,
character except
DLE or invalid
character
W + 1
Send NAK
G
T > T
ADT
,
character except
DLE, STX or
invalid characters
Send NAK
High
priority
Low
priority
1
BCC only with 3964(R)
x = setup attempt counter
T
ADT
=500 ms (3964(R) T
ADT
=2s)
W = transmission attempt counter
Immediate return to initial state at line break (BREAK)
DLE
STX
x = 1
x + 1
Send NAK
G
x <= 6
x > 6
x <= 6
x > 6
Receipt not
permitted
3964(R)
Figure 2-18
Flow Diagram of Sending with the 3964(R) Procedure
Содержание SIMATIC CP 440
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Страница 134: ...Diagnostics with the CP 440 8 16 Point to point connection CP 440 Installation and Parameter Assignment A5E00057742 02 ...
Страница 164: ...Accessories and Order Numbers D 2 Point to point connection CP 440 Installation and Parameter Assignment A5E00057742 02 ...