Siemens SITRANS FST030 - Integer Byte Order; Float Byte Order; Modbus Function Codes

A.5 Integer byte order
The device is able to adjust the byte order of integer values.
Table A-4 Integer byte order
Modbus
register
Data type /
Size in
bytes
Parameter Description Default value
[units]
(units register)
Value range /
Setting op‐
tions
Access
level
8295 Unsigned /
2
Integer order byte The integer byte order used
in Modbus messages.
0: MSB - LSB (big endian)
1: LSB - MSB (little endian)
MSB = most significant byte /
high byte
LSB = least significant byte /
low byte
MSB - LSB
(big endian)
0 - 1 Read /
write
A.6 Float byte order
The device is able to adjust the byte order of floating-point values.
Table A-5 Float byte order
Modbus
register
Data type /
Size in
bytes
Parameter Description Default value
[units]
(units register)
Value range /
Setting op‐
tions
Access
level
8296 Unsigned /
2
Float byte order The float byte order used in
Modbus messages.
0: 1-0-3-2
1: 0-1-2-3
2: 2-3-0-1
3: 3-2-1-0
The first mentioned byte is
the first byte sent.
Byte 3 corresponds to the
left-most byte (MSB) of a 32
bit floating point number in
big endian format, byte 0 to
the right-most byte
3-2-1-0 0 - 3 Read /
write
A.7 Modbus function codes
Table A-6 General Modbus settings
Function code Command text Description
01 Read Coils Reads the status of single bit(s)
02 Read Discrete Inputs Reads the status of single input bit(s)
Modbus communication
A.7 Modbus function codes
SITRANS FST030 (Modbus)
138 Operating Instructions, 08/2018, A5E37367739-AD