Modbus TCP

Modbus TCP is a version of the Modbus protocol based on Ethernet, which uses TCP/IP for communication. Unlike the traditional Modbus RTU protocol, Modbus TCP allows devices to be interconnected directly through Ethernet without any special hardware or communication interface. Therefore, Modbus TCP has higher communication speed and wider application range.

In addition to supporting data acquisition and processing via TCP client mode, the Neuron Modbus TCP plugin also supports TCP server mode, which allows devices to connect to Neuron actively. This feature is mainly used for 4G DTU because the IP address of 4G network is a private IP. In this case, the DTU device can only connect to Neuron actively.

Plugins

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