Rockwell Automation 1761 MicroLogix 1000 Programmable Controllers - Manual (Page 331)

Understanding the Communication Protocols
D–3
DF1 Full-Duplex Protocol
DF1 Full-Duplex communication protocol combines data transparency (ANSI —
American National Standards Institute — specification subcategory D1) and 2-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 its user manual,
publication 1761-6.2).
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 retries None N retries
③
DLE ENQ retries 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.
➂
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.