Ethernet Communications Modules, 3rd Edition, Rev. D
5-16
Chapter 5: MODBUS TCP for H0/H2/H4-ECOM100
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Modbus Function Codes Supported
The H0/H2/H4 -ECOM100 supports the following Modbus function codes when acting as a
Modbus TCP client.
Modbus
Function Code
Function
DL05/06/205/405
Data Types Available
01 Read Output Table Y, C, T, CT
02 Read Input Table X, SP
03
Read holding registers (when addressing mode
is 584/984, this function is used to access
analog output registers)
V
04
Read Input Registers (when addressing mode is
584/984, this function is used to access analog
input registers)
V
15 Force Multiple Outputs Y, C, T, CT
16 Preset Multiple Registers
V
NOTE: The H0/H2/H4- ECOM100, as a client/master, supports function code 4. Thus, 30001 address
ranges can be read from a server/slave device.
This is done by specifying an odd number of bytes transfered instead of the normal even number of bytes.
Thus: Even number of bytes to transfer: RX/WX for the Holding Registers (400001+ address range).
Odd number of bytes to transfer: RX for the Input Registers (30001+ address range). It is not possible to
use WX on 30001 address ranges because by definition Input Registers are "read-only."
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