Rockwell-automation 2755-DM9, -DM9E High Speed Decoder Bedienungsanleitung PDF herunterladen (Seite 114)

Chapter 8

Host Commands Using the RS-485 Interface

8–2

You can use RS-485 PCCC to communicate with a host programmable

controller using a PCCC format. The following diagram illustrates a PCCC

command.

00000010

01000001

DATA MAXIMUM OF 122 BYTES

HI Byte LOW Byte

10010010 00110000

10001000 00000000

01110000 00000010

128

The diagram illustrates both the high byte and low byte of each data word

(word = 2 bytes). Data is always transmitted with the low byte of each data

word first and then the high byte. The numbers on the diagram indicate the

order in which data bytes are transmitted.

PCCC Command Format

The Programmable Controller Communications Commands (PCCC) are sent

in packets of data having the following structure.

STATUS

COMMAND

TRANSACTION WORD

HI-ADDRESS

LOW-ADDRESS or

FUNCTION CODE

DATA

HI Byte LOW Byte

128

The LOW-byte is always sent out first and then the HI-byte. The following

are descriptions of each field of the command:

RS-485 PCCC Command

Protocol

1 2 ... 109 110 111 112 113 114 115 116 117 118 119 ... 166 167

Keine Kommentare

Rockwell-automation 2755-DM9, -DM9E High Speed Decoder Bedienungsanleitung Seite 114