DOCA0355EN-00

Data Types

The TeSys Tera system supports the following Modbus RTU data types:

Name

Description

Range

INT16

16-bit signed integer (1 word)

-32768...+32767

UINT16

16-bit unsigned integer (1 word)

0...65535

UINT32

32-bit unsigned integer (2 words)

0...4 294 967 295

UINT64

64-bit unsigned integer (4 words)

0...18 446 744 073 709 600 000

BOOL

1-bit data

0–1

ASCII

String of 8-bit alphanumeric character

Table of ASCII characters

BITMAP

16-bit field (1 word)

NOTE:

INT16, UINT16, and ASCII data are transmitted with big-endian coding by default:

  • The most significant byte is transmitted first.

  • The least significant byte is transmitted second.

UINT32 and UINT64 data are transmitted with big-endian coding by default:

  • The most significant byte of the most significant word is transmitted first.

  • The least significant byte of the most significant word is transmitted second, and so on.

The byte format setting can be changed to little-endian, refer to Modbus RTU Port Settings.

Endianness

Endianness is the order in which bytes within a word of digital data are transmitted through a data communication medium. Endianness is represented in two ways:

  • Big Endian:

    A big-endian system stores the most significant byte at the smallest memory address and the least significant byte at the largest memory address.

  • Little Endian:

    A little-endian system stores the most significant byte at the largest memory address and the least significant byte at the smallest memory address.

Example of Endianness

Data Type Value Value in Hexadecimal Big-endian Little-endian
UINT16/INT16 1000 03E8 03 E8 E8 03
UINT32/INT32 70000 00011170 00 01 11 70 70 11 01 00
UINT64/INT64 100000 00000000000186A0 00 00 00 00 00 01 86 A0 A0 86 01 00 00 00 00 00

Date and Time

The date and time in data logs is coded in four UINT16 data.
Data Type Range Description
1 UINT16 0x01–0x1F MSB: Day
0x01–0x0C LSB: Month
2 UINT16 0x00–0x63 MSB: Year

0–99 (0x00–0x63) corresponds to years 2000 to 2099

For example, 0x17 (23) corresponds to year 2023

0x00–0x17 LSB: Hours
3 UINT16 0x00–0x3B MSB: Minutes
0x00–0x3B LSB: Seconds
4 UINT16 0x0000–0x03E7

Milliseconds

For setting date and time, refer to the Real-Time Clock (RTC) Settings.

Modbus Register

The address of register number n is n-1. The tables detailed in the following parts of this document provides both register numbers (in decimal format) and corresponding addresses (in hexadecimal format).

For example, the address of register number 20 is shown in the following table:

Data

Address (Decimal)

Address (Hexadecimal)

20

19

0x0013

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