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TASK 5 (EtherNet/IP Option)
ETHERNET/IP EXPLICIT MESSAGING
5.1 Required Message Instructions
Only two instructions are required to transfer data between the PLC and the SMD17E2. One instruction reads
data from the unit and the other writes data to it. The sample programs available from AMCI use this style of
programming. The two instructions are alternately triggered using the instruction’s ENABLE bits. The
remainder of the program controls when data in the source tags of the write instruction changes. The follow
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ing table gives the required attributes for the instructions.
Table T5.1 Message Instruction Attributes
Only RSLogix 500 version 8.0 or above can be used to configure Message Instructions to
communicate with an EtherNet/IP device. Message Instructions do not work correctly in ver-
sion 10 of RSLogix 500.
5.2 Create Four New Data Files.
An Integer file to contain the data read from the SMD17E2. This file must be at least 10 words
in length.
An Integer file to contain the data written to the SMD17E2. This file must be at least 10 words in
length.
A Message (MG) data file. This file must have at least two elements, one to control the Read
Operation and one to control the Write Operation.
An Extended Routing Information (RIX) data file. This file is used to store information used by
the Message Instructions. This file must have at least two elements, one for the Read Operation
and one for the Write Operation.
All controllers that support EtherNet/IP support explicit messaging. When using
explicit messaging, Message Instructions must be added to your program to com
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municate with the SMD17E2. Explicit messaging can be use on platforms that also
support implicit messaging.
Rockwell Automation controllers which are programmed with the RSLogix 500
software only support explicit messaging. A MicroLogix 1100 will be used as an
example in this chapter.
Read Instruction Write Instruction
Service Type Read Assembly Write Assembly
Service Code E (hex) 10 (hex)
Class 4 (hex) 4 (hex)
Instance 100 (decimal) 150 (decimal)
Attribute 3 (hex) 3 (hex)
Length 20 bytes 20 bytes
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