TCP Gateway slave number
If you are using a TCP Gateway, you must select the appropriate slave number for
the configuration of the data points.
Addressing:
The information is stored in the Modbus Slave device in 4 different tables. 2 tables store on/off
discrete values (coils) and two store numerical values (registers). Each coil is 1 bit long and
assigned a data address between 0 and 65535. Each register has the size of 1 word(16 bits/ 2
bytes) and has a data address between 0 and 65535.
Coil/ Register numbers Data addresses Function type Table name
1-9999 0 to 65535 1 Read Coils
10001-19999 0 to 65535 2 Read Inputs
30001-39999 0 to 65535 4 Read Input Registers
40001-49999 0 to 65535 3 Read Holding Registers
Coil / register numbers can be considered as location names since they do not appear in the
configuration. The Data Addresses (Start Address) are used in the configuration.
Data Types:
Data type Length Data range
BOOLEAN 1 bit True to False
INT 4 bytes
−2147483648 to 2147483647
LONG 8 bytes
−9223372036854775808 to 9223372036854775807
DOUBLE 8 bytes
-9.9999999999999999999999999999999999999E+125 to
9.9999999999999999999999999999999999999E+125
STRING
1 - 255
bytes
Modbus data types:
Data
type
Length
Data type
number
Data range
char 8 bits 1 -128 to 127
unsigned
char
8 bits 2 0 to 255
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