Endress+Hauser Proline Promass E 100 - Byte Transmission Sequence

System integration Proline Promass E 100 Modbus RS485
46 Endress+Hauser
INTEGER
Data length = 2 bytes (1 register)
Byte 1 Byte 0
Most significant byte (MSB) Least significant byte (LSB)
STRING
Data length = depends on the device parameter, e.g. presentation of a device parameter with a data length = 18
bytes (9 registers)
Byte 17 Byte 16 ... Byte 1 Byte 0
Most significant byte (MSB) ... Least significant byte (LSB)
9.2.5 Byte transmission sequence
Byte addressing, i.e. the transmission sequence of the bytes, is not specified in the Modbus
specification. For this reason, it is important to coordinate or match the addressing
method between the master and slave during commissioning. This can be configured in
the measuring device using the Byte order parameter.
The bytes are transmitted depending on the selection in the Byte order parameter:
FLOAT
Sequence
Options 1. 2. 3. 4.
1 – 0 – 3 – 2 * Byte 1
(MMMMMMMM)
Byte 0
(MMMMMMMM)
Byte 3
(SEEEEEEE)
Byte 2
(EMMMMMMM)
0 – 1 – 2 – 3 Byte 0
(MMMMMMMM)
Byte 1
(MMMMMMMM)
Byte 2
(EMMMMMMM)
Byte 3
(SEEEEEEE)
2 – 3 – 0 – 1 Byte 2
(EMMMMMMM)
Byte 3
(SEEEEEEE)
Byte 0
(MMMMMMM)
Byte 1
(MMMMMMM)
3 – 2 – 1 – 0 Byte 3
(SEEEEEEE)
Byte 2
(EMMMMMMM)
Byte 1
(MMMMMMMM)
Byte 0
(MMMMMMMM)
* = factory setting, S = sign, E = exponent, M = mantissa
INTEGER
Sequence
Options 1. 2.
1 – 0 – 3 – 2 *
3 – 2 – 1 – 0
Byte 1
(MSB)
Byte 0
(LSB)
0 – 1 – 2 – 3
2 – 3 – 0 – 1
Byte 0
(LSB)
Byte 1
(MSB)
* = factory setting, MSB = most significant byte, LSB = least significant byte
STRING
Presentation taking the example of a device parameter with a data length of 18 bytes.
Sequence
Options 1. 2. ... 17. 18.
1 – 0 – 3 – 2 *
3 – 2 – 1 – 0
Byte 17
(MSB)
Byte 16 ... Byte 1 Byte 0
(LSB)