Ethernet Communications Modules, 3rd Edition, Rev. D
5-28
Chapter 5: MODBUS TCP for H0/H2/H4-ECOM100
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A
B
C
D
The ECRX will read from Slave ID "1", and will target address TA0 (V0) which is the
Modbus equvalent address 40001 ( first Holding Register).
It will get 4 bytes ( 2 registers) and place the data in V2000-2001. This data will likely be in
decimal format if coming from 3rd party devices. The DataView window at left has V2000
-2001 set for Decimal format.
Note that Workspace V location must be unique.
The ECWX will write to Slave ID "1", and will target address TA2 ( V2) which is the
Modbus equivalent of 40003 ( third Holding Register).
It will write 4 bytes (2 registers) from the PLC addresses V7766-V7767 . These 2
addresses are the Seconds and Minutes from the PLC RealTime Clock, so they are nonzero
most of the time. Note the data will be in BCD/Hex format.
The DL05 will only have data here if using the Option module D0-01MC, otherwise it will
be zeroes.
Note that Workspace location must be unique.
NOTE: If trying to read Modbus Input Registers ( Function Code 4 or 30001 addressing),
the # of bytes must be increased by 1 to the next odd number. This is how the
DirectLogic and ECOM100 recognize the Modbus address is an Input Register.
ECOM100 RX Network Read
ECRX
ECOM100#
Workspace
Slave ID
From Slave Element (Src)
Number of Bytes
To Master Element (Dest)
Success
Error
IB–740
K1
V503
K1
TA 0
K4
V2000
C100
C101
ECOM100 WX Network Write
ECWX
ECOM100#
Workspace
Slave ID
From Slave Element (Src)
Number of Bytes
To Slave Element (Dest)
Success
Error
IB–741
K1
V504
K1
V7766
K2
TA 2
C102
C103
4
5
6
C106
C106
NOP
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