Rockwell Automation 1763 MicroLogix 1100 Programmable Controllers User Manual - Manual (Page 204)

Publication 1763-UM001D-EN-P - March 2011
202 Connecting to Networks via RS-232/RS-485 Interface
Example DF1 Half-Duplex Connections
Considerations When Communicating as a DF1 Slave
on a Multi-drop Link
When communication is between either your programming software and a
MicroLogix Programmable Controller or between two MicroLogix 1100
Programmable Controllers via slave-to-slave communication on a larger
multi-drop link, the devices depend on a DF1 Half-Duplex Master to give each
of them access in a timely manner. As the number of slave devices increase, the
time between when slave devices are polled also increases. This increase in
time may also be large if you are using low baud rates. As these time periods
grow, you may need to increase the poll timeout and reply timeout values for
slave devices.
TERM A B COM SHLD CHS GND TX
TX PWR
TX
DC SOURCE CABLE
EXTERNAL
TERM A B COM SHLD CHS GND TX
TX PWR
TX
DC SOURCE CABLE
EXTERNAL
TERM A B COM SHLD CHS GND TX
TX PWR
TX
DC SOURCE CABLE
EXTERNAL
Rockwell Software RSLinx 2.0 (or
later), SLC 5/03, SLC 5/04, and SLC
5/05, PLC-5, MicroLogix 1100, or
MicroLogix 1200 and 1500
processors configured for DF1
Half-Duplex Master.
RS-232
(DF1 Half-Duplex Protocol)
MicroLogix
1500 (Slave)
SLC 5/04
(Slave)
MicroLogix
1000 (Slave)
SLC 5/03 with
1747-KE Interface
Module (Slave)
MicroLogix
1200 (Slave)
Modem
MicroLogix
1100 (Slave)
IMPORTANT
If a program download is started when using DF1
Half-Duplex, but then is interrupted due to
electromagnetic interference or other events,
discontinue communications to the controller for the
ownership timeout period and then restart the
program download. The ownership timeout period is
60 seconds. After the timeout, you can re-establish
communications with the processor and try the
program download again. The only other way to
remove program ownership is to cycle power on the
processor.