Modbus tcp function codes This command is writing the By using function codes, Modbus RTU ensures that the master device can accurately request data from or send data to slave devices, facilitating efficient and reliable communication in industrial automation systems. The Request PDU specifies the starting register address and the number of registers. bytes(0)=MSB of MSW Function code & Description: Word: 3: 04 (read input register: read current binary value in one or more input registers) 06 (write single register: write a binary value to a holding register) MODBUS TCP Slave (All function) Supported series: MODBUS TCP controller. The Request: Here are how the bytes are defined in Modbus Function Code 16 - To Write Multiple Numeric registers Home About MODBUS fc01 fc02 fc03 fc04 fc05 fc06 fc15 fc16 ASCII TCP exceptions About Enron MODBUS RTU Master RTU Slave TCP Client Download Purchase Contact . func _code: function code: Unsigned integer (8 bits) 1. Each function code corresponds to a particular type of operation, such as reading or writing data. Je cherche à faire communiquer un PLC Unitronics V350 avec le ColorControl. Display Filter Reference: Modbus/TCP. This command is requesting the content of analog input register # 30009 from the slave device with address 17. 11 04 0008 0001 B298. the address of the first input specified, and the number of inputs. 11: The Slave Modbus Reference excerpt from GCP Reference Manual. Modbus TCP/IP Functions; Modbus TCP/IP Exception Codes; Function 8: Modbus Diagnostics; Function 43-14: Read Device Identification (Basic) Function 43-15: Read Date and Time; Function 43-16: Write Date and Time; Function 100-4: Read Non-Adjacent Registers; Appendix B: Data Availability. 0 to 1. ) but it doesn't work as I want, so I ask you here. 3. They can also read/write data on coils and holding The Modbus messaging service provides a client/server communication between devices connected on an Ethernet TCP/IP network. Modbus function 01 can be used to read the status of such an output. For function codes carrying a variable amount of data in the request or response, In this article, you will learn the Modbus communication protocol function codes and address range with examples. Data send to ip: 01 02 03 ea 00 05. These options are used to find errors during the driver The Modbus Master sends requests to the Modbus Slaves in the form of Modbus function codes. Modbus TCP - Function code 0x03 (read holding registers) - reverse_order boolean option #44553. Skip to content. Things I do not understand is: function code 03 shall be used to read holding register (analog out) function code 04 shall be used to read input register (analog input) Modbus/TCP is an adaptation of the serial Modbus protocol for TCP/IP communication. A forum for topics related to the scope of Modicon PAC offers and ecosystem along the whole lifecycle: Modicon M580 and 340, EcoStruxure Control Expert, EcoStruxure Process Expert (Unity Pro) and more. Modbus Function Code 4 Read Input Registers on Modbus. Unraveling Modbus TCP Exception Codes. or _mask: Modbus TCP compatible master to read and write control date. 3. They specify the type of action that a Modbus master wishes to perform. Overview. This command is requesting the ON/OFF I am using citectSCADA to read current/voltage value from power meter via Modbus TCP/IP protocol. We recommend to use ID 100, since many Modbus-TCP clients and PLCs do not work with ID 0. Versions: 1. On the New Device page, leave all the default values and type in the following fields:. The Modbus TCP client supports the following function blocks from the PLCCommunication library without any configuration: o ADDM. The Modbus Master sends the function code along with other information, such as the address of the slave device and the register or memory location to be Outline (1) Data Model Blocks / Memory Areas (2) Flowcharts of Modbus Master and Slave (3) Modbus Breakdown in the Context of the TCP/IP Five-Layer Model (4) Framing and Deframing in Modbus (5 Several versions of the Modbus protocol exist such as Modbus RTU, Modbus ASCII, Modbus TCP and Modbus Plus. Pymodbus synchronous forwarder. 0 to 4. This command is writing the 4. 2 Modbus Message Framing ASCII Framing In ASCII mode, messages start with a ‘colon’ ( : ) character (ASCII 0x3A), and end with a ‘carriage return – line feed’ (CRLF) Here are how the bytes are defined in Modbus Function Code 02 - To Read Multiple Boolean on/off values Home About MODBUS fc01 fc02 fc03 fc04 fc05 fc06 fc15 fc16 ASCII TCP exceptions About Enron MODBUS RTU Master RTU Slave TCP Client Download Purchase Contact . It is used for reading contents on a contiguous block of holding registers in a remote device. MODBUS function codes are elements of MODBUS request/reply PDUs. This command is requesting the content The communication is half duplex. Closed grezco opened this issue Dec 15, 2020 · 21 comments · Fixed by #48544. When working with Modbus TCP functions, it is important to have a thorough understanding of the various here the overview, if you are Master (ModBusMaster. Read Coils - 0x01. 1 Function Code 1, Read Coils The Modbus/TCP feature supports reading and writing of single-bit Coils and 16-bit Holding Registers, as Modbus TCP/IP Exception Codes. All Modbus function codes follow a similar pattern to the two Here are how the bytes are defined in Modbus Function Code 15 - To Write Multiple Boolean on/off values Home About MODBUS fc01 fc02 fc03 fc04 fc05 fc06 fc15 fc16 ASCII TCP exceptions About Enron MODBUS RTU Master RTU Slave TCP Client Download Purchase Contact . Closed grezco opened this issue Dec 26, 2020 · 12 comments · Fixed by #49719. This command is writing the Joined: 4/5/2018. Force Single Coil (Function Code=05) Request. FC04 Read Input Registers. To do this, add the channels in the tab "Modbus Slave Channel". Full Modbus TCP setup information can be found in the GCP Reference Manual, A5E03944542001 12/2019 (Rev 3) 2000584-001 Overview 1 Modbus Address Map 2 Host/Analyzer Messages 3 Modbus Protocol Reference 4 Appendix A - Contact Information A Appendix B - Change Log B. This command is requesting the ON/OFF Modbus Function Code 3 Read Multiple Holding Registers on Modbus. It is based on a controller-peripheral (formerly known as master-slave) architecture and communication between nodes is achieved with send request and read response type messages. They allow you to read or write data, query device information, perform control actions, and more. The device documentation must specify which Function Codes are supported by the device from the list of public Function Codes. victronenergy. This is a repeater or converter and an example of just how powerful datastore is. This command is requesting the content Appendix A: Details of Modbus Functions. It consist of a server (any comm) and a client (any comm MODBUS fc01 fc02 fc03 fc04 fc05 fc06 fc15 fc16 ASCII TCP exceptions About Enron MODBUS RTU Master RTU Slave TCP Client Download Purchase Contact . Modbus TCP/IP or Modbus TCP — This is a Modbus variant used for communications over TCP/IP networks, connecting over port 502. Last visit: 1/24/2024. Therefore input registers numbered 1-16 are addressed as 0-15. The protocol these devices are using is Modbus. The Function Code (read Analog Output Holding Registers) 006B: The Data Address of For function codes where the request and response are of fixed length, the function code alone is sufficient. Modbus forwarder Source: examples/modbus_forwarder. 20, the Modbus RTU driver no longer requires the Serial Support Gateway module to function. J'ai déjà bien avancé, la communication est établie mais je ne réussi pas à recevoir les données sur le V350. This command is writing the Here are how the bytes are defined in Modbus Function Code 03 - To Read Multiple Numeric registers Home About MODBUS fc01 fc02 fc03 fc04 fc05 fc06 fc15 fc16 ASCII TCP exceptions About Enron MODBUS RTU Master RTU Slave TCP Client Download Purchase Contact . Function code is 1 byte which gives the code of the function to execute. Common Modbus function codes Function 01: Read coil status. Please see the Modbus specification for more information. The The below table clearly summarizes the Modbus function codes. A Modbus master sends a request to a Modbus slave which performs actions and responds to the master. Modbus TCP requires that you know or define IP addresses on the network. len: length: Unsigned integer (16 bits) 1. you need to connect to a Slave to write Subset of Modbus Function Codes Supported The following table shows the functions codes supported by this application. (I would communicate with the windows program(as a client) using the modbus-tcp. By using these function codes, a client can request a wide range of data from a server, making Modbus TCP/IP a versatile protocol for Here are how the bytes are defined in Modbus Function Code 05 - To Write a Single Boolean on/off value Home About MODBUS fc01 fc02 fc03 fc04 fc05 fc06 fc15 fc16 ASCII TCP exceptions About Enron MODBUS RTU Master RTU Slave TCP Client Download Purchase Contact . e. 8. 3 Modbus/TCP Function Codes. Data structure offsets . So, I'm trying to code the client and server in the linux environment. In this scenario, a master is often a PLC, with field devices behaving as the slaves. Field name Description Type Versions; modbus _tcp. Closed Modbus TCP - Function code 0x03 (read holding registers) - 3. from publication: Communication Protocols of an Industrial Internet of Things Environment: A Comparative Study | Most industrial and The second parameter in each Modbus message is the function code. I don't have any unit in my device Modbus TCP/IP Unplugged – An introduction to Modbus TCP/IP Addressing, Function Codes and Networking. The range of acceptable addresses for Modbus Serial devices is 1 to 247. One of the following events can occur after a request from the master: o The exception response's exception function code is the same as the original request function code plus 128 (0x80). General Description. 0x04. The data field of the PDU has the address from 0 to MODBUS is a request/reply protocol and offers services specified by function codes. jpg ) and you try to add slave functions codes you see them. The Function Code (read Analog Output Holding Registers) 006B: The Data Address of the first register requested. system in the excel sheet, and use Unit-ID 100. This command is requesting the ON/OFF when using a Modbus TCP to Modbus Serial gateway. Function codes are essential aspects of the Modbus protocol. This defines the message type and the type of action required by the slave. In Modbus TCP, the message is “wrapped” and sent over a computer network instead of serial data cables. In the original intended use case, a Modbus TCP/IP to serial gateway could be used to allow connection between new TCP/IP networks and older serial Modbus uses a master/slave model for communication (client/server in Modbus TCP). FC03 Read Holding Registers. Read Holding Registers (Function Code=03) Request. There are several function codes. For function codes carrying a variable amount of data in the request or response, the data portion will be preceded by a byte count. For the overall system data, look for com. The problem is when we try to establish the connection with these devices using Modbus TCP/IP driver from the computer,all the device I'm gonna to read/write under the modbus-tcp specification. Services on Modbus are specified by function codes. Modbus TCP server Implement a Modbus TCP server exposing Modbus commands to control LEDs. The objective of this document These memory registers can be read or manipulated using function codes. 16: modbus _tcp. The following functions are supported by Modbus Poll. Stubs at the meter connec- Ethernet allows to daisy-chain the Modbus TCP/IP communication through 2 RJ45 ports on the devices. o What is a function code in Modbus? Modbus TCP (Transmission Control Protocol): Modbus TCP, which uses Ethernet for communication, is a logical development of the Modbus protocol. The next step is to define the Modbus TCP Channel Configuration, but when I do this, I find that I only have the options of the following function codes for the channel: Read Holding Registers (Function Code 03) Write Multiple Registers (Function Code 04) Read/Write Multiple Registers (Function Code 23) And there is no function code 02, 04 etc. 0. The 4 data Modbus TCP/IP. The Modbus conformance test supports four types of data references: These entities play a crucial role in managing and making sense of data within the Modbus framework. Protocol field name: mbtcp. TCP/IP. In the PDU Registers are addressed starting at zero. Menu; The most efficient method of transporting bulk information of any type over Modbus us to use function codes 3 (read registers), 16 (write registers) or possibly 23 (read/write registers). One is the actual Modbus TCP protocol, the other is Modbus RTU-over-TCP. If there are no specific PLC restrictions, then the client generally supports the following function codes: FC01 Read Coils. Posts: 5. This gives the Modbus interface definition a very long lifetime. Modbus RTU over Modbus TCP: A TCP/IP protocol with an additional CRC check. Force Multiple Coils (Function Code=15) Request. Public. Download Table | Function codes for data access in MODBUS. It offers advantages such as faster data transmission, support for larger data payloads, and the ability to On plain old RS232 are the same messages used as on Modbus/TCP over Ethernet. Closed Modbus TCP - Function code 0x03 (read holding registers) - reverse_order boolean option #44553. o READ_VAR Modbus Function Code 2 Read Discrete Inputs on Modbus. In some cases, you also need unit ID's. Note: Modbus Write Single Coil, function code 05, writes a single coil to the PLC. In Modbus language, a coil is a discrete output value. There are several command line debug options for the Modbus/TCP driver. For Modbus Clients (RTU/TCP) In addition to the Modbus commands defined in the configurator We have 15 devices connected to 1 serial to ethernet converter and then this converter is connected to the computer. These protocols are used together and are the transport protocol for the internet. Unit Address. Modbus TCP. In addition to the standard function codes, Modbus TCP also supports custom function codes for specific applications or devices. 1 Topology The RS-485 bus uses line topology, see figure below. The S7-1200 CPU is Modbus TCP server. Modbus RTU is a serial communication protocol, typically using RS-232 or RS-485 interfaces, while Modbus TCP/IP is Using MBP_MSTR block's function code 15 (Send Modbus Request), to read 3xxxx register via Modbus TCP on M580. name: power slave: 1 Function: 2 address: 1002 coils: 5; that is the goal. The parameter contains one byte of information. If needed additional The Modbus Server/Client is included in the firmware, and does not require any programming action from the user. The function code is the first item to be validated. The Request PDU specifies the starting address, i. But for a few corresponding applications, these might not get applied. The NO is that the function sets for Modbus TCP/IP communications in Concept and Proworx do not support this function code. BM85 S985 984A/B AND MODBUS PLUS MAP HOST PROCESSOR HOST/MMI AT/MC–984 AND S980 (TO MAP) 984–685 AND MODBUS UP TO FOUR MODBUS DEVICES OR NETWORKS P230 PROGRAMMER Modbus Function Codes. In both cases, TCP is a transport protocol that carries Modbus messages. There is also a Modbus TCP Master Sample application for when a master is desired, i. 01 (0x01) Read Coils 02 (0x02) Read Discrete Inputs 03 (0x03) Read Holding Registers 04 (0x04) Read Input Registers 05 (0x05) Write Single Coil 06 (0x06) Write Single Register Here are how the bytes are defined in Modbus Function Code 01 - To Read Multiple Boolean on/off values Home About MODBUS fc01 fc02 fc03 fc04 fc05 fc06 fc15 fc16 ASCII TCP exceptions About Enron MODBUS RTU Master RTU Slave TCP Client Download Purchase Contact . Modbus ASCII uses a subset of the ASCII character set to send Modbus TCP port 502 diagnostics . These are used to read data from discrete inputs and input registers. Function codes are integer values, ranging from 1 to 255, and the range from 128 to 255 is for exception responses. TCP is Transmission Control Protocol and IP is Internet Protocol. o When they are reset by a Modbus command (function code 8, sub-function code 10). PowerTag Data Re: Modbus code 17 with Modbus TCP/IP. 2 Cable Suitable cables for Modbus TCP/IP connection: For example, function code 3 is used to read multiple holding registers, while function code 16 is used to write multiple registers. Only the Modbus functions handled by the circuit breaker are described here. This version of Modbus is implemented Modbus TCP operates at the application layer of the TCP/IP stack and utilizes the same function codes as the serial versions of Modbus. 0x7F. 2. Read Coil Status (Function Code=01) Request. These function codes are pivotal as they define the specific action to be executed on a data 1) The I/O devices' settings and extra information can be accessed under the Modbus code of 70 (0x46), and there are sub functions which I will need to use in order to read and/or write the settings. 0x05 to 0x7E. Mapping example The purpose of this example is to show how to interpret the information in Modbus TCP has Format Slave ID; Function Code; Adress, num of coils. MODBUS Function Code Function DL05/06/205 /405 Data Types Available 01 Read Output Table Y, C, T, CT 02 Read Input Table X, SP 03 Read Holding Registers (when addressing Modbus tcp code function 91: Modbus: 2: Jul 12, 2002: Similar threads; Modbus TCP/IP Platform That Can Send Different Function Codes: Supported Function Codes in MODBUS TCP: ModBus/TCP Function 16 - No Response: Function code 17 in Modbus/TCP: Modbus tcp code function 91: You May Also Like. 2Function codes32003-ModbusTCP_Function Codes-PNOZmulti The following function codes (FC) are available for communication with the modular safety system PNOZmulti via Modbus/TCP: Function code Function FC 01 Read Coils The Client in a connection reads bit data from the Server in the con-nection, data length ≥ 1 Bit, content: input/output data I do not need my own function codes, but I just need to make a scenario that uses different function codes (except of function code 1 and 3 that Max,Min avg temperature has). This command is writing the contents of Modbus TCP/IP messages contain a Modbus Application Protocol header, a Function code indicating the message operation, and the Data field, which varies depending on the Function code. Thus, a Modbus TCP/IP Application Data Unit (ADU) takes the form of a 7 byte header (transaction identifier + protocol identifier + length field + unit identifier), and the protocol data unit (function code + data). The following is an example of how to parse modbus messages using the supplied framers. 117. I'm testing the client code for linux as a client and the easymodbus as a server. 5. so function code is a must have. in case the plc is modbus slave (ModbusSlave_FC-Code. Exception responses issued by the master or a slave can be the result of data processing errors. Note that both Unit-ID 0 and Unit-ID 100 map to the same internal address. It is only Modbus tcp is Modbus encapsulated in tcp frame that means that MB tcp remain Modbus serial at the basics and therefore datas are stored in same format for instances: for 32 bits values, don't care if it is long var or real var, or neither xx function code, we just need to take in count that we want to send 4 bytes. If the function code is not recognized by the device receiving the request, it responds with an exception. FC05 Write Single Coil. Rating: (0) Hello, I have a problem with device, that should communicate through Modbus TCP, but there is only Function code 23 which i found it is not supported by siemens function MB_Client. As far as I know, the answer is YES and NO. When Modbus is carried over TCP, additional length information is carried in the prefix to allow the The Modbus function code 23 (0x17) gives the opportunity to execute an atomic write/read operation. The Modbus protocol offers a number of functions that are used to read or write data over the Modbus network. For example, the Modbus TCP standard encapsulates individual Modbus data frames as TCP/IP packets, which are then (usually) encapsulated again as Ethernet packets to arrive at the destination device. The request PDU consists of 5 bytes: Offset Length Description Values; 0: Byte: Function Code: 05: 2: Word: First coil address: 0000h to FFFFh: 4: Word: Modbus TCP functions provide a set of predefined operations that can be performed on registers. Modbus/TCP Driver - Details The Modbus The Modbus PDU. The maximum Modbus TCP message length is 260 bytes. Back to Display Filter Reference. A Modbus Messaging Modbus TCP: A TCP/IP protocol. 1. Services requested by the client are specified by function codes (FCxx), and can be found in the specification or documentation of the API below. Function Field. Here are how the bytes are defined in Modbus Function Code 01 - To Read Multiple Boolean on/off values Home About MODBUS fc01 fc02 fc03 fc04 fc05 fc06 fc15 fc16 ASCII TCP exceptions About Enron MODBUS RTU Master RTU Slave TCP Client Download Purchase Contact . FC02 Read Discrete Inputs. 1. I need to construct some demo procedures that use function code 2,4,5,6,15 and 16 or just send some function codes manually (I know the sequence of function codes that one specific This article proposes to enhance the new Modbus/TCP Security protocol with authentication and authorization functions that guarantee security against intentional unauthorized access. This TCP/IP is implemented on an Ethernet network and all the data interactions from client/master are forwarded towards server/slave via IP address. In this section we go through Modbus function codes and explain the specifics of data frame construction for each one of them. In this example we'll select Modbus TCP, and click Next. This “multi-layered” approach inherent to Modbus being such a high-level protocol may seem cumbersome, but it offers great flexibility in that Modbus TCP - Function code 0x03 (read holding registers) - Cannot use all registers read #44254. With benefits in speed, range, Modbus Functions. . Reserved for other public codes . see About Modbus TCP | Simply Modbus Software Modbus Message Parser. Preset Multiple Registers (Function Code=16) Request. It is used for reading from 1 to 125 contiguous input registers in a remote device. For function codes where the MODBUS PDU has a fixed length, the function code alone is sufficient. The S7-1500 CPU establishes the first connection as Modbus TCP client. Modbus Modbus/TCP client, receives requests from Modbus functions and sends response messages. Read Input Registers (Function Code=04) Request. Function Codes for Read/Write Operations: Data access within the Modbus protocol is determined by the function code field within the Modbus data frame. Modbus TCP Client. The Server does not have a SlaveID since it uses an IP Address instead. Modbus TCP-to-serial gateway Implement a gateway between an Ethernet TCP-IP network and a Modbus serial line. Name: Modbus; Hostname: Type the IP address. In the PDU Discrete Inputs are addressed starting at zero. TCP exceptions About Enron MODBUS RTU Master RTU Slave TCP Client Download Purchase Contact . In this code snippet, we create a Modbus TCP client that connects to a server and reads two holding registers. Each segment of the code is crucial for understanding how Modbus operates From the figure, we see that the function code and data fields are absorbed in their original form. Visit the European website. 1 Function codes Now the function codes to transmit data needs to be specified. Function Code in Request: Function Code in Exception Response: 01 (01 hex) 0000 0001: The exception codes as explained in the Modbus specification are: Exception Code: Name: Meaning: 01 (01 hex) Illegal Starting in version 8. Modbus TCP vs RTU-over-TCP. There are several function codes of Modbus that will access its registers. Modicon PAC Forum. This is from the GX Modbus-TCP Manual. Supported Modbus-TCP function codes The supported function codes are: ReadHoldingRegisters = 3 ReadInputRegisters = 4 WriteSingleRegister = 6 WriteMultipleRegisters = 16 Note that there is no difference between function code 3 and 4. 2. I figured out Modbus function 03 shall be used to get the reading. These custom function codes enhance flexibility and adaptability in Modbus TCP Library about creating frames in Modbus TCP/IP protocol and connecting with slave and manipulate by function codes. the Modbus protocol imbedded into each network’s packet structure provides the common language by which the devices can exchange data. 11: The Slave MODBUS fc01 fc02 fc03 fc04 fc05 fc06 fc15 fc16 ASCII TCP exceptions About Enron MODBUS RTU Master RTU Slave TCP Client Download Purchase Contact . The S7-1200 CPU establishes the second connection as Modbus TCP client. This function code is used for reading from 1 to 2000 contiguous discrete inputs on a remote device. The Modbus protocol also offers diagnostic and network-management functions. The Modbus/TCP driver can be used for Modbus/TCP or UNICOS at the same time. The Function Code field tells the addressed slave what function to perform. Note: Although the protocol selected for the HMI is MODBUS TCP MODBUS TCP "ERROR PROCESSING FUNCTION CODE 3" Bonjour, je viens vous demander de l'aide concernant le Modbus TCP. Due to this feature, it is accessible in RUNNING, STOPPED and EMPTY states. In this example, two Modbus functions are connections. 4 4. The Function code tells the peripheral device if it The H0/H2/H4–ECOM100 supports the following MODBUS function codes when acting as a MODBUS TCP/IP server. (40108-40001 = 107 =6B hex) 0003: The total number of Here are how the bytes are defined in Modbus Function Code 15 - To Write Multiple Boolean on/off values Home About MODBUS fc01 fc02 fc03 fc04 fc05 fc06 fc15 fc16 ASCII TCP exceptions About Enron MODBUS RTU Master RTU Slave TCP Client Download Purchase Contact . In the example program, the function code 23 (Read/Write Multiple Registers) to read and write Here are how the bytes are defined in Modbus Function Code 16 - To Write Multiple Numeric registers Home About MODBUS fc01 fc02 fc03 fc04 fc05 fc06 fc15 fc16 ASCII TCP exceptions About Enron MODBUS RTU Master RTU Slave TCP Client Download Purchase Contact . Read Functions The architecture of Modbus TCP/IP or Modbus communication protocol using TCP is shown below. For example, a VFD might use the discrete inputs or registers to start, Each command starts with an address followed by a function code. For example, 10. There exists only one subcategory of these codes. The messages are constructed in a format that allows them to be easily processed and understood by devices in the network. jpg): Supported Function Codes If not restricted by a special type of the controller, the slave generally supports the following function codes: The Modbus RTU message consists of the address of the SlaveID device/Device Address, the function code, the special data, depending on the function code and the CRC of the checksum. For example, Func 07 (0x46), Sub func 6 (0x06), can be used to set the communications settings of a module. The device uses these memory registers to control or monitor itself. Modbus TCP port 502 connection table . 20. The address range applies to each type of register, and one needs to look at the function code in the Modbus message 3. 6. py. Exception Responses. 4. Read Input Status (Function Code=02) Request. - rrnax/ModbusTCPIP Here are how the bytes are defined in Modbus Function Code 03 - To Read Multiple Numeric registers Home About MODBUS fc01 fc02 fc03 fc04 fc05 fc06 fc15 fc16 ASCII TCP exceptions About Enron MODBUS RTU Master RTU Slave TCP Client Download Purchase Contact . The client/server model is based on four type of Simply put, this is a Modbus RTU message transmitted with a TCP/IP wrapper and sent over a network instead of serial lines.
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