Ethernet Tcp/Ip Configuration; Multicast Configuration; Igmp Implementation - Lenze SMVector Reference Manual

2.2 Ethernet TCP/IP Configuration
Typically, an EtherNet/IP network is made up of segments containing point-to-point connections in a star
configuration as illustrated in Figure 2. At the center of this star topology is a bank of Ethernet 2 & 3
switches that can support a great number of point-to-point nodes.
2.2.1 MultiCast Configuration
By default the SMVector drive automatically generates the multicast address used for I/O messaging.
The default multicast TTL (time to leave) value is 1 which means that the multicast I/O packets will be
propagated over the local subnet only.
The user is allowed to explicitly set the drive's multicast address and TTL values but this feature should
be used carefully. The TTL and Mcast Config attributes in the TCP/IP object are also implemented. Note
that the Num Mcast value in the Mcast Config attribute must always be 1. The user configurable SMVector
system variables for multicast are:
Variable ID Meaning
426 TTL
422-425 Multicast address (default 239.64.2.224)
2.2.2 IGMP Implementation
The IGMP v2 version of the IGMP (Internet Group Management Protocol) is used.
CMVETH01B
Introduction
Application-Specific
Object
Parameter
Object
Explicit
Messages
Connection Manager
UCMM
Figure 2: EtherNet/IP Star Configuration
0 7 8
Type
Max Response Time
Message Type Max Response Time
0x11 General Query Maximum time the Querier
waits for report in response
0x12 v1 Report
to a membership query
0x16 v2 Report
0x17 v2 Leave
0x22 v3 Report
In a general query it is the multicast group address
In other cases it is a specific multicast address
Figure 3: IGMP v2 Message Format
Identity
Object
Message Router Assembly
Object Object
I/O
Messages
Object
TCP/IP Ethernet
15 16 23 24
Checksum
Group Address
Checksum
The 1's complement
of the entire IGMP message
Group Address
4
TCP/IP Interface
Object
Ethernet Interface
Object
Network
31