Siemens SIMATIC TIWAY 1 User Manual

Page 182

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USING THE NON-INTELLIGENT TERMINAL PROTOCOL

UNILINK HOST ADAPTER

A-6

USER MANUAL

Figure A–2 illustrates how a TIWAY I Primitive is enclosed in the adapter
command string which is enclosed in the NITP message structure.

Length

Primitive

Code

Descriptor

Field(s)

Data Unit

Field(s)

Command Code

Secondary

Address

Network Data

TIWAY I Primitives

:

Adapter Data

Check Sum

UNILINK Host Adapter Commands

Message

Character

Count

;

NITP Protocol Message Frame

Figure A–2

Illustrative NITP Message Structure

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