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Rockwell Automation Publication 2080-UM002N-EN-E - November 2022
Chapter 5 Communication Connections
Here are some configuration examples based on the limits described in the table above:
1. The maximum number of drives that can be controlled over EtherNet/IP is 16. This is
due to the maximum limit of TCP Client connections is 16, and the maximum limit of
EtherNet/IP Client connections is also 16.
2. If you have 10 devices controlled over EtherNet/IP, the maximum number of devices
that can be controlled over serial is six. This is due to the maximum limit of Client
connections is 16.
3. The total number of UDP sockets plus TCP Client/Server sockets has a maximum limit
of eight.
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, see the Connected Components Workbench Online Help. For more
information about the Modbus protocol, see Modbus Protocol Specifications available from
.
For information on Modbus mapping, see
Modbus Mapping for Micro800 on page 261
.
To configure the serial port as Modbus RTU, see
Configure Modbus RTU on page 64
.
Connection Limits for Micro830/Micro850/Micro870 Controllers
Description
Micro830
Micro850/
Micro870
CIP Connections
Total number of client plus server connections for all ports
16
24
Maximum number of client connections for all ports
15
16
Maximum number of server connections for all ports
16
24
Maximum number of EtherNet/IP connections
Client
–
16
Server
23
Maximum number of USB connections
Client
–
–
Server
15
23
Maximum number of Serial connections
Client
15
16
Server
15
23
TCP Connections
Total number of client plus server connections
–
64
Maximum number for EtherNet/IP
Client
16
Server
16
Maximum number for Modbus TCP
Client
16
Server
16
Maximum number for User Programmable Sockets
8
User Programmable Sockets
Total number of User Programmable Sockets
(any combination of UDP plus TCP Client/Server)
–
8
IMPORTANT
If all client/server connections are fully loaded, performance may be
affected, such as data loss and intermittent delays during
communication.
Use MSG_MODBUS instruction to send Modbus messages over serial port.