Rockwell Automation DAG6.5.8 APPLICATION GUIDE SCADA SYSTEM - Manual (Page 351)

Publication AG-UM008C-EN-P - February 2005
Basic DF1 Protocol Troubleshooting B-5
Table B.2 Identify the DF1 Half-Duplex Packets
See ANSI X3.4, CCITT V.3, or ISO 646 for the standard definition of
these characters.
Symbol Hexadecimal Binary Type Meaning
DLE SOH 10 01 0001 0000 0000 0001 control symbol Start of header
Sender symbol that indicates the start of a
master station’s message
DLE STX 10 02 0001 0000 0000 0010 control symbol Start of text
Sender symbol that separates the multi-drop
header from the data
DLE ETX BCC/CRC 10 03 xx(xx) 0001 0000 0000 0011 control symbol End of text and checksum
Sender symbol that terminates a message
DLE EOT 10 04 0001 0000 0000 0100 control symbol End of transmission
Response symbol used by remote stations as a
response to a poll when they have no
messages to send
DLE ENQ STN
BCC 10 05 xx xx 0001 0000 0000 0101 control symbol Enquiry poll packet
Sender symbol, issued only by the master
station, that starts a poll command
DLE ACK 10 06 0001 0000 0000 0110 control symbol Acknowledgment
Response symbol which signals that a
message has been successfully received
DLE DLE 10 10 0001 0000 0001 0000 data symbol Represents the data value or STN value of 10
(hex)
DLE NAK 10 15 0001 0000 0001 0101 control symbol Global link reset command only issued by the
master station during powerup or a serial port
reconfiguration
The command causes the remote station to
cancel all messages that are ready to transmit
to the master station. Typically, the remote
station returns an error code to the affected
MSG instructions.
STN application specific data symbol Station number of the remote station on your
half-duplex link (00-FE)
APP DATA application specific data symbol Single characters having values 00-0F and
11-FF
Includes data from application layer including
user programs and common application
routines