Example
Data
type
Function
type
Start
address
Variable
type
Response
Address
Offset
Response
Quantity
Example
Data
type
Function
type
Start
address
Variable
type
Response
Address
Offset
Response
Quantity
Reading the first Holding Register, number
40001, has the Data Address 0.
int
Read
Holding
Registers
0
unsigned
short or
short
0 1
VariableType: 4 or 3 (unsigned short or
short)Reading the second Input Register,
number 30002, has the Data Address 1.
int
Read
Input
Registers
1
unsigned
short or
short
0 1
Reading a float (32 bits) from Input Register
30108 / 30109, has the Data Address 107.
double
Read
Input
Registers
107
float
(reads
two
registers)
0 1
Reading a string. This example describes to
read four letters from register 400006 and
400007. Each register contains two
characters.
string
Read
Holding
Registers
5
unsigned
short
0
2
(registers)
Using Modbus register addresses directly
Usually, it is necessary to enter Modbus registered address decremented by 1 as "start address",
but it may lead to confusion when comparing the data point's "start address" with the registered
address from Modbus device's manual. Therefore, enter a negative value in the "response
address offset" field to directly use the registered address from the Modbus device's manual as
"start address". In case a negative value has been entered as "response address offset", this value
will internally be subtracted from the given "start address" number to read the data from
Modbus device. Positive "response address offset" values will be handled to address specific data
within the read data if several registers need to be read to acquire the data from Modbus device
as data block and the necessary data itself is only a part of that data block.
Supported since:
MindConnect Nano V03.04.03.03 b001
Samples:
Using decremented
start address
Using address
from manual
Getting data from a read
data block
Registered address from Modbus
device manual
303 303 64001
Start address 302 303
64001
1)
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