Rockwell Automation 1770-HT8 SMART TRANSMITTER - Manual (Page 104)

Chapter 4
C Communicating with the Smart
Transmitter Interface
4-39
In both full duplex and half duplex mode the DF1 responses from the
Smart Transmitter Interface are identical. These responses are sent
immediately by the Smart Transmitter Interface in full duplex mode.
However, in half duplex mode the host must first send a poll to the Smart
Transmitter Interface before it will send the DF1 Response. Figure 4.17
and Figure 4.18 illustrate the format and an example of these responses.
Figure 4.17
DF1 Packet sent by the Smart Transmitter Interface to a Host Computer
DLE
90080
STX DST SRC APPLICATION DATA DLE ETX BCC/CRC
CMD STS TNS
SCMD CHN ERR STA DATA
LEN DATA
Smart Transmitter
Interface Packet
Data Link
Layer Packet
Since message is from host to Smart Transmitter Interface
DLE = data link escape control character (10" hex)
STX = start of text control character ("02"hex)
DST = host station address in hexadecimal
SRC = Smart Transmitter Interface station address in hexadecimal
CMD = 4F" hexadecimal
STS = status byte
TNS = transaction number (2 bytes)
LEN = length of Smart Transmitter Interface Packet in bytes
SCMD = Smart Transmitter Interface Command
CHN = Smart Transmitter Interface Channel
ERR = Smart Transmitter Interface Error Code
STA = Smart Transmitter Interface Status
ETX = end of text control character (03" hex)
BCC/CRC = Block Check or CRC bytes