Timeout; Message Cycle; Byte Order; Structure Of A Message - Trumeter 898X Serie Manual De Instrucciones

5.3 Timeout

If the Master device does not receive a response within 0.5 seconds, it can discard the last request.

5.4 Message cycle

A message cycle ≤ 0.5 sec. is supported.

5.5 Byte order

The Modbus protocol uses the Big Endian format.

5.6 Structure of a message

Pauses within the transmission of a message
Pauses with a length >= 1.5 characters between the single message bytes lead to an error in the data frame.
Start and end identification
A message pause with a length of 3.5 characters is specified as start and end identification of a message.
This pause must be respected between the single messages.

5.7 Function codes

The following function codes are supported.

5.8 Data values

The 32 bit data values are transmitted via MODBUS either in the Integer or in the Float format. The register
address defines the format to be used.

5.8.1 Float format (32 bits)

The Float values are coded in compliance with the IEEE 754 standard (single floating point) and have the
following structure.
SEEEEEEE EMMMMMMM MMMMMMMM MMMMMMMM
E
X S M
= ×
The data conversion in the floating point representation generates conversion errors (rounding error) due to
the limited number of mantissa bits.
Slave Address Function code Data
1 byte 1 byte
Function code
03
hex
10
hex
11
hex
Address X + 1
Byte 4 Byte 3
CRC
N bytes 2 bytes
description
Read several registers
Write several registers
Identification of the Slave
Address X
Byte 2 Byte 1
S: Sign
E: Exponent
M: Mantissa
X: Total value
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