Active and Passive Partners

Send/Receive requires a point-to-point TCP connection between the communications partners. One partner is responsible for initiating the connection request while the other is responsible for

accepting or rejecting the request. The partner responsible for initiating the request to establish the connection is called the Active partner. The partner that responds to the connection request is called the Passive partner. To establish a peer-to-peer connection one partner must be Active and the other Passive.

NOTE:

The connection is full duplex. Once the connection has been established, both partners may use the connection to send and receive data.

Here is a link to the full manual, maybe you can find enough information here to help you out.

http://support.automation.siemens.com/WW/view/en/17519012

Hope this helps,
Daniel Chartier