Type
| Function block |
Description
| The function block is used to send data via TCP (Transmission Control Protocol) to a TCP-capable Ethernet device. This is done using an IP socket. The IP socket must first be opened using the TCP_SOCKET function block before data can be sent.Each transmission operation is triggered by a rising edge at the request REQ input. During this cycle, the function block copies the data to be sent (applied to the DATA input) into an internal buffer. The BUSY output is set to TRUE as long as data are being sent from the internal buffer. While BUSY = TRUE, the REQ input is ignored. The transmission of new data that are available at the DATA input during the ongoing transmission cycle can only be triggered with a rising edge at the REQ input once the BUSY output has been set to FALSE.If the connection is broken and the communication partner cannot be reached, the ERROR output is set to TRUE for one cycle. The corresponding error code is provided at the STATUS output within this cycle.
Unintended machine operation Verify that the influence of the output data cannot result in an unintended or hazardous behavior of the entire system.1 |
1 | When running the application logic in simulation mode, the function blocks for Ethernet communication establish a real connection to other devices/servers. Thus, outputs and variables connected to real hardware may be set and therefore may cause real damage to the machine. |
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Notes
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- The IP socket opened by the TCP_SOCKET function block can only be used for subsequent calls of the TCP_SEND function block as long as the ACTIVE output of the TCP_SOCKET function block is TRUE. Calling the TCP_SEND function block while ACTIVE = FALSE causes an error at the TCP_SEND function block (ERROR = TRUE and STATUS code = 0xC210 issued).
- For controllers with integrated firewall, make sure that the firewall does not block the ports involved in the communication. Otherwise, the connection cannot be established.
- Function blocks have to be instantiated.
The instance name of the function block has to be declared in the 'Variables' table of the POU where the FB is going to be used. The instance name must be unique within the POU.
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Parameters
| Inputs
REQ
Data type: | BOOL |
Description: | A rising edge at the request REQ input triggers the transmission of the data applied to the DATA input. The input is ignored as long as data are being sent (BUSY = TRUE).All other input parameters are evaluated with a rising edge at the REQ input in case that BUSY = FALSE. |
HANDLE
Data type: | DWORD |
Description: | Socket handle that has been opened with the TCP_SOCKET function block (see also the notes above). The parameter is only evaluated in the cycle in which the REQ parameter switches to TRUE. |
DATA_CNT
Data type: | UDINT |
Description: | Number of bytes to be sent from the DATA buffer (DATA_CNT = DATA_CouNT). The maximum number of bytes to be sent is limited to the maximum value of 2147483647 bytes. If the value is 0 (= initial value of the parameter), the entire variable connected to DATA will be sent.The parameter is only evaluated in the cycle in which the REQ parameter switches to TRUE.
Tip: You can use the SIZEOF function to determine the size of a variable (number of bytes reserved for the variable in the controller memory). |
Input/Output
DATA
Data type: | ANY |
Description: | Data buffer which contains the data to be sent.Data is transmitted as byte stream. There is no Little-/Big-Endian conversion. If the data type of the connected variable is a STRUCT (or ARRAY OF STRUCT), the byte stream may contain padding bytes. |
Outputs
DONE
Data type: | BOOL |
Description: | Set to TRUE once the data has been sent successfully. The output is set for only one cycle. |
BUSY
Data type: | BOOL |
Description: | Set to TRUE while the system is trying to send the data. As long as the parameter is set to TRUE, the REQ input is ignored. |
ERROR
Data type: | BOOL |
Description: | If an error occurs, the ERROR output is set to TRUE. The corresponding error code can be read at the STATUS output while ERROR = TRUE.In case of a detected error, the output is set to TRUE for only one cycle. The error code must be read at the STATUS output within this cycle.See Error Codes / Status Codes for Ethernet FBs. |
STATUS
Data type: | WORD |
Description: | Provides the error code in the event of an error (ERROR = TRUE) or the current status of the function block (ERROR = FALSE). Error codes start with 16#Cxxx and status codes with 16#8xxx.See Error Codes / Status Codes for Ethernet FBs. |
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