I need an API that help me read/write data from/to an Allen Bradley PLC.
The communication protocol of the PLC is Ethernet/IP.
An existing alternative is to use OPC to communicate, but it requires the OPC Server, which as a certain cost.
The API would be used by either a windows service written in .net or web server application in .net or in php. Therfore the API should be in .NET or any other web server compatible runtime like PHP. This can be redefined depending on your skills.
Allen Bradley PLC's website at Rockwell Automation provides documentation for the communication: [url removed, login to view]