Rockwell-automation 1770, D17706.5.16 Ref Mnl DF1 Protocol Command Manual de usuario descargar pdf (Pagina 35)

2–6 Understanding DF1 Protocol

Publication

17706.5.16 - October 1996

Both half-duplex and full-duplex protocols are character-oriented.

They use the ASCII control characters in the tables below, extended

to eight bits by adding a zero for bit 7:

Table 2.A

Halfduplex Protocol

Abbreviation

Hexadecimal Value Binary Value

STX 02 0000 0010

SOH 01 0000 0001

ETX 03 0000 0011

EOT 04 0000 0100

ENQ 05 0000 0101

ACK 06 0000 0110

DLE 10 0001 0000

NAK 0F 0000 1111

Table 2.B

Fullduplex Protocol

Abbreviation

Hexadecimal Value Binary Value

STX 02 0000 0010

ETX 03 0000 0011

ENQ 05 0000 0101

ACK 06 0000 0110

DLE 10 0001 0000

NAK 0F 0000 1111

(For the standard definition of these characters, refer to the ANSI

X3.4, CCITT V.3, and ISO 646 standards.)

A symbol is a sequence of one or more bytes having a specific

meaning to the link protocol. The component characters of a

symbol must be sent one after another with no other characters

between them. DF1 protocol combines the characters listed in the

tables above into control and data symbols:

• Control symbols are fixed symbols required by the DF1 protocol

to read a particular message

• Data symbols are variable symbols which contain the application

data for a particular message

Transmission Symbols

1 2 ... 30 31 32 33 34 35 36 37 38 39 40 ... 250 251

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Rockwell-automation 1770, D17706.5.16 Ref Mnl DF1 Protocol Command Manual de usuario Pagina 35