3-1
3
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Modbus master function
3.1 Overview
This is the function for obtaining data from a general-purpose device supporting ModbusRTU such
as ModbusRTU-supported controller, ModbusRTU-supported sensor and recording the data on this
device. With this device as the master, a maximum of 12 supported devices can be connected under
it. The data to be obtained are specified individually on this device side. The data obtained can be
assigned to the calculating channels of the main unit.
With communication IDs, a maximum of 12 slave connection destinations can be selected. By
setting the slave ID (station number), Modbus address, register type, data type and data count for
each ID in accordance with the slave device's specifications, this device obtains data from the slave
devices with a fixed interval (1/2/5 seconds) and stores the data inside it. If the data to be obtained
are sequential, a maximum of 16 data can be obtained with a single ID.
If the data are not sequential or the register types are different, acquire the data with multiple IDs.
For the slave devices, the following parameters are set from this device side.
Item
Name
Range
Remarks
01
Communication ID
01 to 12
02
Slave ID
(Station number)
0 to 247
0 means "Disabled", If 0 is set, communications do
not occur.
03
Address
0 to 9999
Relative address
04
Register type
Input/hold
ModbusRTU's function code
Func04/03
can be set.
05
Data format
INT16
UINT16
INT32(BIG/LITTLE)
UINT32(BIG/LITTLE)
FLOAT(BIG/LITTLE)
1 word
1 word
2 words
2 words
2 words
06
Decimal point
position
0 to 4
Disabled when FLOAT is set
07
Number of data
1 to 16
Number of data received sequentially
