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Detailed flowcharts appendix d – Rockwell Automation 1770-KF2 Data Highway or Highway Plus Interface Module User Manual User Manual

Page 223

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Detailed Flowcharts

Appendix D

DĆ19

Figure D.24

Receiver Routine for FullĆDuplex Protocol

RCVE

Reset Buffer Flag: Set
Header to Illegal Value

GET BUFFER

Get a Buffer

LAST = NAK

Reset Receiver Error Flag

GET CODE

Get Next Input

Control
Code
?

DLE ENQ
?

DLE STX
?

XMSG

Transfer Message to
Network Layer

Ignore
Flag (0)
?

Save Response (ACK or
NAK) in LAST

SEND CTL

Transmit
LAST

No

Yes

No

Yes

No

Yes

Yes

No

NOTE: XMSG Returns ACK,
NAK, or 0 (for Ignored Message)

Variables

LAST: Value of Last Response

HEADER: DST, SRC, CMD, STS

and TNS from Last Message

BUFFER: Whether an Empty Buffer Is Read

Receiver Error Flag

11654