Rockwell Automation Publication 2080-UM002N-EN-E - November 2022 75
Chapter 6          Micro870 Controller Distributed Network Protocol
Max Random Delay (x1 ms)
This parameter is used with Pre-transmit Delay (x1 ms) for Collision Avoidance on RS-485 
network. For more details, see Collision Avoidance
 on page 112.
The valid range is 0…65535. Default value is 0.
Ethernet Layer Configuration Parameters
The DNP3 over IP subsystem in the controller supports Listening End Point, TCP Dual End Point 
and Datagram End Point type. 
Listening End Point type supports a single TCP connection as a Server and UDP datagram. 
TCP Dual End Point type supports a single TCP connection as a Server, a single TCP connection 
as a Client and UDP datagram. 
Datagram End Point type supports UDP datagram from DNP3 Masters. The default TCP and UDP 
port numbers are 20000 and the port numbers are configurable.
The End Point type can be determined by the parameter End Point Type. According to the 
parameter, the controller works as different End Point types. See Table 6
 for each 
configuration.
The parameter DNP3 over IP Enable is configured in the Ethernet configuration page and other 
parameters are configured in the DNP3 Slave configuration page.
Table 6 - End Point Types
End Point Type Connection Description
Listening End Point
A single TCP server connection
Any of the requests are accepted and the responses 
are transmitted via this connection.
The unsolicited responses are transmitted via this 
connection when this connection is available.
UDP datagram
Accepts only broadcast packets when DNP3 
destination node is one of 0xFFFD, 0xFFFE and 
0xFFFF in the request.
Dual End Point
A single TCP server connection
 Any of the requests are accepted and the responses 
are transmitted via this connection.
The unsolicited responses are transmitted via this 
connection when this connection is available.
This connection has higher priority than the Client 
connection.
A single TCP client connection
Any of the requests are accepted and the responses 
are transmitted via this connection.
The unsolicited responses are transmitted via this 
connection when this connection is available.
The controller does not request TCP client connection 
to DNP3 Master until an unsolicited response is 
generated.
UDP datagram
Accepts only broadcast packets when DNP3 
destination node is one of 0xFFFD, 0xFFFE and 
0xFFFF in the request.
Datagram End Point UDP datagram only
Any of the requests are accepted and the responses 
are transmitted via this connection.
All responses can be transmitted to the different 
DNP3 Master port according to the configuration of 
the parameters Remote UDP Port Number and Master 
IP Address0. If this parameter is not set to 0, the 
solicited responses are sent to the DNP3 Master port 
that is configured. If this parameter is set to 0, the 
solicited responses are sent to the DNP3 Master port 
that sent the request.
TCP connection is not available in this configuration.