Modbus RTU

Modbus RTU is a version of the Modbus protocol that is based on serial communication. Unlike the Modbus TCP protocol, Modbus RTU is typically used to connect sensors, actuators, and other control devices on a factory production line. It is a fast, reliable, and flexible serial communication protocol that provides reliable data transmission and control functions.

The Modbus RTU protocol uses binary encoding and can transmit data over RS-232, RS-485, or other serial communication media. The Modbus RTU plugin for Neuron adds an implementation based on Ethernet TCP and enables remote device data acquisition and control through a DTU device.

Parameters

Data types

• INT16
• UINT16
• INT32
• UINT32
• INT64
• UINT64
• FLOAT
• DOUBLE
• BIT
• STRING

Address format

SLAVE!ADDRESS[.BIT][#ENDIAN][.LEN[H][L][D][E]]

SLAVE

Required, Slave is the slave address or site number.

ADDRESS

Required, Address is the register address.The Modbus protocol has four areas, each area has a maximum of 65536 registers, and the address range of each area is shown in the table below. It should be noted that the storage area as large as 65536 is generally not required in practical applications. Generally, PLC manufacturers generally use an address range within 10000. Please pay attention to fill in the correct point address according to the area and function code of the device.

tip Some device specification documents may use function codes and register addresses to describe commands. Since register address numbers start at 0, the register address range for each area is 0 to 65535. Neuron uses a PLC configuration address specification, so the addresses configured in Neuron start from 1.

The conversion rule for the configuration address specification is as follows: determine the highest digit of the address based on the function code, and add 1 to the register address to obtain the address used in Neuron.

For example, if the function code is 0x03 and the register address is 0, the address used in Neuron is 400001. If the function code is 0x02 and the register address is 5, the address used in Neuron is 100006.

.BIT

Optional, specify a specific bit in a registe

#ENDIAN

Optional, byte order, applicable to data types int16/uint16/int32/uint32/float, see the table below for details. | Symbol | Byte Order | Supported Data Types | Note | | —- | ———- | ————————— | ——- | | #B | 2,1 | int16/uint16 | | | #L | 1,2 | int16/uint16 | Default byte order if not specified | | #LL | 1,2,3,4 | int32/uint32/float | Default byte order if not specified | | #LB | 2,1,4,3 | int32/uint32/float | | | #BB | 3,4,1,2 | int32/uint32/float | | | #BL | 4,3,2,1 | int32/uint32/float | |

.LEN[H][L][D][E]

When the data type is STRING, .LEN is a required field, indicating the number of bytes the string occupies. Each register contains four storage methods: H, L, D, and E, as shown in the table below. | Symbol | Description | | —- | ——————————————————- | | H | One register stores two bytes, with the high byte first | | L | One register stores two bytes, with the low byte first | | D | One register stores one byte, and it is stored in the low byte | | E | One register stores one byte, and it is stored in the high byte|

Examples