FB_IotHttpRequest

This function block enables the PLC to send HTTP commands to the server that has been configured with the function block FB_IotHttpClient. To be able to process an HTTP response, the output bBusy of this function block must first return FALSE. Then the content payload, specific header fields or a JSON string can be extracted from the response.

Syntax

Definition:

FUNCTION_BLOCK FB_IotHttpRequest IMPLEMENTS ITcIotHttpResponse
VAR_INPUT
    sContentType     : STRING((ParameterList.cSizeOfHttpContentType-1)) :='text/html;charset=UTF-8';
    eCompressionMode : E_IotHttpCompressionMode                         := 'E_IotHttpCompressionMode.NoCompression';
END_VAR
VAR_OUTPUT
    bBusy            : BOOL;
    bError           : BOOL;
    eErrorId         : ETcIotHttpRequestError;
    nStatusCode      : UINT;
    nContentSize     : UDINT;
END_VAR

Inputs

Name	Type	Description
sContentType	STRING	Content type of the request, e.g. the initial value "text/html; charset=UTF-8".
eCompressionMode	E_IotHttpCompressionMode	Enumeration of the different compression modes. Further information is provided in the chapter Compression. The list can be found in the Appendix.

Outputs

Name	Type	Description
bBusy	BOOL	This output remains TRUE until the function block has executed the command.
bError	BOOL	Becomes TRUE as soon as an error situation occurs.
eErrorId	ETcIotHttpRequestError	Enumeration of status code on transport level e.g. if a certificate validation has failed. The enumeration can be found in the Appendix.
nStatusCode	UINT	HTTP status code send from the server within the response.
nContentSize	UDINT	Size of the content payload.

Methods

Name	Description
GetContent	Reads the response from the HTTP server.
GetHeaderField	Reads the value from a specified header field.
GetJsonDomContent	Parses the server response as JSON object.
SendJsonDomRequest	Sends a request to the server as JSON object.
SendRequest	Sends a HTTP command to the server.
SendXmlDomRequest	Sends a request to the server as an XML object.

Requirements

Development environment	Target platform	PLC libraries to include
TwinCAT v3.1.4024.7 or higher	IPC or CX (x86, x64, ARM)	Tc3_IotBase

Further Information