Read and Write PLC Variables via HTTP Interface

The PLC variable interface provides these features and advantages:

• A simple HTTP interface is used to read/write PLC variables.
• Multiple variables can be read /written in single HTTP request at the end or start of a PLC cycle.
• Quick application development.
  • The interface allows a user to quickly develop applications in many languages (e.g., Java, C#, and C++).
• Platform independence.
  • Applications can be developed on any platform supporting HTTP.
• Remote access.
  • Variables may be read/written from a remote machine.
• Security.
  •  There is an Authorization mechanism which enables access to the interface.
  • See Configure the Controller.
• Support for both JSON and text (raw) formats to send/receive requests or responses.
• Support for all basic PLC data types:

  BOOL	SINT	USINT
  BYTE	INT	UINT
  WORD	DINT	UDINT
  DWORD	LINT	ULINT
  LWORD	REAL	LREAL
  TIME	STRING

There are two interfaces:

• A variable READ interface which is used to read a set of PLC variables.
• A variable WRITE interface which is used to write a set of PLC variables.

The URL is same for both interfaces: (controller URL)/kas/plcvariables