Table of Contents
Ethernet Communications Modules, 3rd Edition, Rev. D
iv
Second RX/WX Instruction .....................................................................................4–19
Third RX/WX Instruction ........................................................................................4–19
Shift Register ..........................................................................................................4–20
Store If Equal ..........................................................................................................4–20
First RX/WX Instruction ..........................................................................................4–21
Second RX/WX Instruction .....................................................................................4–21
Third RX/WX Instruction ........................................................................................4–21
Chapter 5 - Modbus TCP for H0/H2/H4-ECOM100
Modbus TCP .............................................................................................................. 5-2
Client / Server Model ............................................................................................... 5-2
Protocol Description ................................................................................................. 5-2
Supported Modbu Function Codes ........................................................................... 5-4
Network Server (Slave) Operation ............................................................................ 5-5
Modbus Function Codes Supported ......................................................................... 5-5
Determining the Modbus Address ............................................................................ 5-5
If Your Host Software or Client Requires the Data Type and Address ........................ 5-6
Example 1: V2100 .................................................................................................. 5-11
Example 2: Y20 ...................................................................................................... 5-11
Example 3: T10 Current Value ................................................................................ 5-11
Example 4: C54 ...................................................................................................... 5-12
If the Host Software or Client Requires an Address ONLY ....................................... 5-12
Example 1: V2100 .................................................................................................. 5-14
Example 2: Y20 ...................................................................................................... 5-14
Example 3: C54 ...................................................................................................... 5-14
Network Client (Master) Operation ....................................................................... 5-15
PLC Memory Supported for Client Operation ......................................................... 5-17
Example 1: Calculating Word PLC Address ............................................................. 5-18
Example 2: Calculating Discrete Input PLC Address ................................................ 5-18
Building the Read (RX) or Write (WX) Routine ........................................................ 5-19
Step 1: Identify ECOM Slot Location and Server Node # ........................................ 5-19
Step 2: Load Number of Bytes to Transfer .............................................................. 5-20
Step 3: Specify Master Memory Area ...................................................................... 5-20
Step 4: Specify Slave Memory Area ........................................................................ 5-20
Communications from a Ladder Program ............................................................... 5-21
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