Basler DECS-250, Instruction Manual

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9440300990 Rev J 203
DECS-250 Modbus™ Communication
Example: The value 95,800 represented in long integer format is hexadecimal 0x00017638. This number
will read from two consecutive holding registers as follows:
Holding Register Value
K (Hi Byte) hex 76
K (Lo Byte) hex 38
K+1 (Hi Byte) hex 00
K+1 (Lo Byte) hex 01
The same byte alignments are required to write.
Integer Data Format (Uint16) or Bit-Mapped Variables in Uint16 Format
The Modbus integer data format uses a single holding register to represent a 16-bit data value.
Example: The value 4660 represented in integer format is hexadecimal 0x1234. This number will read from
a holding register as follows:
Holding Register Value
K (Hi Byte) hex 12
K (Lo Byte) hex 34
The same byte alignments are required to write.
The Uint16 Data Format is listed in Binary Points (Table 25) , below .
Example: Register 900 occupies 16 rows in the Register Table where each row gives the name of specific
bit-mapped data such as 900-0 indicates bit 0 of register 900 is mapped to RF-TRIG.
Short Integer Data Format/Byte Character Data Format (Uint8)
The Modbus short integer data format uses a single holding register to represent an 8-bit data value. The
holding register high byte will always be zero.
Example: The value 132 represented in short integer format is hexadecimal 0x84. This number will read
from a holding register as follows:
Holding Register Value
K (Hi Byte) hex 00
K (Lo Byte) hex 84
The same byte alignments are required to write.
String Data Format (String)
The Modbus string data format uses one or more holding registers to represent a sequence, or string, of
character values. If the string contains a single character, the holding register high byte will contain the
ASCII character code and the low byte will be zero.
Example: The string “PASSWORD” represented in string format will read as follows:
Holding Register Value
K (Hi Byte) ‘P’
K (Lo Byte) ‘A’
K+1 (Hi Byte) ‘S’
K+1 (Lo Byte) ‘S’
K+2 (Hi Byte) ‘W’
K+2 (Lo Byte) ‘O’
K+3 (Hi Byte) ‘R’
K+3 (Lo Byte) ‘D’