Rockwell Automation 1761-HHP-B30 MicroLogix 1000 with Hand-Held Programmer (HHP) - Manual (Page 428)

Appendix D
Understanding the Communication Protocols
D–2
DF1 Full-Duplex communication protocol combines data transparency
(ANSI — American National Standards Institute — specification
subcategory D1) and two-way simultaneous transmission with embedded
responses (subcategory F1).
The MicroLogix 1000 controllers support the DF1 Full-Duplex protocol via
RS-232 connection to external devices, such as computers, the Hand-Held
Programmer (catalog number 1761-HHP-B30), or other MicroLogix 1000
controllers. (For information on connecting to the Hand-Held Programmer,
see chapter 3, Connecting the System).
DF1 Full-Duplex Operation
DF1 Full-Duplex protocol (also referred to as DF1 point-to-point protocol) is
useful where RS-232 point-to-point communication is required. This type of
protocol supports simultaneous transmissions between two devices in both
directions. DF1 protocol controls message flow, detects and signals errors,
and retries if errors are detected.
DF1 Full-Duplex Configuration Parameters
When the system mode driver is DF1 Full-Duplex, the following parameters
can be changed:
Parameter Options Default
Baud Rate
Toggles between the communication rate of 300, 600, 1200, 2400,
4800
➀
, 9600, 19200, and 38400
➀
.
9600
➁
Node Address
Valid range is 0–254 decimal for MicroLogix 1000 Series C and later
discrete and all MicroLogix 1000 analog. Not configurable for
MicroLogix 1000 Series A and B discrete.
1
Parity None No Parity
Stop Bits None 1
Error Detection None CRC
DLE NAK
received
None N retries
③
DLE ENQ
received
None N retries
③
ACK Timeout None 1 s
Duplicate Packet
Detection
None Enabled
Control Line None
No
Handshaking
Embedded
Responses
None Enabled
➀
Applicable only to MicroLogix 1000 Series D or later discrete and all MicroLogix 1000 analog controllers.
➁
If retentive communication data is lost, default is 1200 for MicroLogix 1000 Series A, B, or C discrete only. For
MicroLogix 1000 Series D or later discrete and all MicroLogix 1000 analog, if retentive communication data is lost,
baud rate defaults to 9600.
③
N=255 for MicroLogix 1000 Series A and B discrete. N=6 for MicroLogix 1000 Series C and later discrete and all
MicroLogix 1000 analog.
DF1 Full-Duplex Protocol