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LD Language Elements
SR2MAN01 11/2007 143
Modbus Inputs/Outputs
Description A Modbus SR3 MBU01BD extension module may be added onto an extensible
smart relay.
In LD mode, the application cannot access the four 16-bit data exchange words.
Data transfer between master and slave is implicit and completely transparent.
Parameters The Modbus module can be configured only from the programming software (see
the on-line help of the programming software for more information).
Words to be sent
to master
Writing these words to the master is automatically performed by duplication of the
status of the discrete I/Os as follows:
I1 to IG: discrete input states for the SR3 B261BD base.
IH to IR: discrete input states for the SR3 XT141BD extension.
Q1 to QA: Discrete output states for the SR3 B261BD base.
QB to QG: Discrete output states for the SR3 XT141BD extension.
Words sent by
the master.
The words sent by the master are not processed by the smart relay.
These 4 16-bit words have the following addresses (Hexa): 0x0010 / 0x0011 /
0x0012 / 0x0013.
Note: The Modbus module only operates in Modbus slave mode.
ID
0
0
0
IC
0
0
0
IB
0
0
0
IG
0
0
0
IF
0
0
0
IE
0
0
0
I7
IQ
Q7
0
I6
IP
Q6
QG
I5
IN
Q5
QF
IA
0
QA
0
I9
0
Q9
0
I8
IR
Q8
0
I3
IK
Q3
QD
I2
IJ
Q2
QC
I1
IH
Q1
QB
I4
IL
Q4
QE
Modbus Address
(Hexa)
0x0014
0x0015
0x0016
0x0017
Most significant byte Least significant byte