Allen-Bradley 2080-LC20-20QWB User Manual page 56

Chapter 5 Communication Connections
48
Modbus RTU
Modbus is a half-duplex, master-slave communications protocol. The Modbus
network master reads and writes bits and registers. Modbus protocol allows a
single master to communicate with a maximum of 247 slave devices. Micro800
controllers support Modbus RTU Master and Modbus RTU Slave protocol. For
more information on configuring your Micro800 controller for Modbus
protocol, refer to the Connected Components Workbench Online Help. For
more information about the Modbus protocol, refer to the Modbus Protocol
Specifications (available from http://www.modbus.org).
See Modbus Mapping for Micro800 on page 165
mapping. To configure the Serial port as Modbus RTU, see
RTU on page 56.
Use MSG_MODBUS instruction to send Modbus messages over
TIP
serial port.
Modbus/TCP Client/Server
The Modbus/TCP Client/Server communication protocol uses the same
Modbus mapping features as Modbus RTU, but instead of the Serial port, it is
supported over Ethernet. Modbus/TCP Server takes on Modbus Slave features
on Ethernet.
The Micro820 controller supports up to 16 simultaneous Modbus TCP Client
connections and 16 simultaneous Modbus TCP Server connections.
No protocol configuration is required other than configuring the Modbus
mapping table. For information on Modbus mapping, see
Micro800 on page 165.
Use MSG_MODBUS2 instruction to send Modbus TCP message over
TIP
Ethernet port.
CIP Symbolic Client/Server
CIP Symbolic is supported by any CIP compliant interface including Ethernet
(EtherNet/IP) and Serial Port (CIP Serial). This protocol allows HMIs to easily
connect to the Micro820 controller.
CIP Serial, supported on the Micro820 controller, makes use of DF1 Full Duplex
protocol, which provides point-to-point connection between two devices.
The Micro800 controllers support the protocol through RS232 connection to
external devices, such as computers running RSLinx Classic software, PanelView
Component terminals (firmware revisions 1.70 and above), or other controllers
for information on Modbus
Rockwell Automation Publication 2080-UM005B-EN-E - March 2015
Configure Modbus
Modbus Mapping for