Rockwell-automation 1775-KA PLC-3 Communication Adapter Module User Ma Instrukcja Użytkownika Pobierz pdf (Strona 137)

Half-Duplex Protocol

Chapter 11

1110

Figure 11.3

Implementation

of Half-Duplex Protocol

XCVR

Select Station

Poll Selected Station

Start Timeout

Receive

No

Receive

Yes

Message

No

No

Yes

Yes

Set Active Station Flag

Get Message from

Send Message

Start Timeout

Received

Yes

No

3

No

Tell Network Layer

Yes

Remove Station

Active

Yes

3

Yes

Duplicate

Yes

No

Give Message

Send DLE ACK

10053–I

DLE EOT

Message

OK?

Network Layer

DLE ACK

Timeouts

for this

of Failure

Station

Timeouts

for this

from Active List

Message

to Network Layer

No

No

Network

Layer has

?

No

Yes

?

Message?

?

Poll?

?

Message to

send?

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