Y_CO_ModbusTCPServer

This function block enables the controller as a Modbus TCP server and starts listening to a client.

Parameters

*	Parameter	Data Type	Description	Default
VAR_IN_OUT
V	Coils	Yt_CO_TCP_ARR_X_0_65535	Array with 65535 words representing the holding registers. The address range is 0-65535.Function codes: 1 and 15
V	Inputs	Yt_CO_TCP_ARR_X_0_65535	Array with 65535 words representing the holding registers. The address range is 0-65535.Function codes: 2
V	InputRegisters	Yt_CO_TCP_ARR_W_0_65535	Array with 65535 words representing the holding registers. The address range is 0-65535.Function codes: 4
V	HoldingRegisters	Yt_CO_TCP_ARR_W_0_65535	Array with 65535 words representing the holding registers. The address range is 0-65535.Function codes: 3,6,16 and 23
VAR_INPUT
V	Enable	BOOL	The function will continue to execute every scan while Enable is held high and there are no errors.	FALSE
V	Acknowledge	BOOL	Modbus timeouts and IP-errors are acknowledged. The function block is not reinitialized.	FALSE
V	BindIP	STRING	This parameter specifies the IP address of the server controller which listens for incoming connections. If this string is empty (= initial value of the parameter) or contains the value '0.0.0.0', the server listens at every Ethernet adapter of the controller.	STRING#''
V	BindPort	INT	Defines the local port number to which the created socket is bound (necessary for setting up TCP/TLS servers). The selected port number is used by the TCP/TLS server for incoming data. Clients, which want to connect to this server, have to specify the same port number as their DEST_PORT input. If the value is 0 (= initial value of the parameter), the stack assigns a temporary port.	INT#502
V	DestIP	STRING	Only requests from the client with this IP address are accepted. If the string is empty (= initial value of the parameter), any client IP address is accepted.	STRING#''
V	DestPort	INT	Only requests from the client with this IP port are accepted. If the value is 0 (= initial value of the parameter), any client IP port is accepted.	INT#0
V	TimeOut	TIME	Timeout monitoring when there is a write access. After a write function was executed, a write telegram must be received again within the time specified here. A timeout error is reported if this is not the case. Specify the timeout value T#0s to disable this function.	T#0s
VAR_OUTPUT
V	Valid	BOOL	Indicates that the function block is operating normally and the outputs of the function block are valid.
V	Busy	BOOL	Set high upon the rising edge of the Execute input, and reset when Done, CommandAborted, or Error is true. In the case of a function block with an Enable input, a Busy output indicates the function is operating, but not ready to provide Valid information. (No Error)
V	Connected	BOOL	TRUE if the server is connected to a client.
V	Status	WORD	Status of the connection. Please refer to the notes for detailed status word explanation.
V	Error	BOOL	Set high if an error has occurred during the execution of the function block. This output is cleared when 'Execute' or 'Enable' goes low.
V	ErrorID	UINT	If Error is true, this output provides the Error ID. This output is reset when 'Execute' or 'Enable' goes low.
V	Message	STRING	If Error is true, this output provides the Error message. This output is reset when 'Execute' or 'Enable' goes low.
V	AddErrMessage	STRING	If Error is true, this output provides any additional message. This output is reset when 'Execute' or 'Enable' goes low.

Notes

A server function block can connect with only one Modbus client at a time. A unique instance of Y_CO_ModbusTCPServer is required for every connection to a client.

Status	Description
16#0000	Function block is deactivated
16#8000	Function block is operating normally
16#8100	The block is waiting for a connection request from the client

Error Description

See the Function Block ErrorID List.

Supported Function Codes

Read
- 01: Coils
- 02: Discrete inputs
- 03: Multiple holding registers
- 04: Input registers
Write
- 05: Single coil
- 06: Single holding register
- 15: Multiple coils
- 16: Multiple holding registers

Object Type	Access	Size
Coil	Read/Write	1 bit
Discrete input	Read only	1 bit
Input registers	Read only	16 bits
Holding registers	Read/Write	16 bits

Starting Up a Server Connection Example

Once enabled, the Y_CO_ModbusTCPServer FB it will be listening for socket connection requests from a client. Once connected, the Valid and Connected outputs are TRUE. Status is 16#8000.

Setting Up Multiple Servers Example

For each client a new TCP server needs to be instantiated.

If two clients have to share data on the server, the VAR_IN_OUT variables can be shared between the two instances that service each client.

Modbus TCP Server response time

The Modbus TCPServer's response time to a function code is roughly between (2 x PLC task time where the Y_CO_ModbusTCPServer is running) and (3 x PLC task time where the Y_CO_ModbusTCPServer is running). Shown below is an example of data transfer when the Y_CO_ModbusTCPServer is running in an 8 ms task.