Setting the Send/Receive Mode 

Purpose

CPI-C works in two-way-alternate mode. This means that at any one time, only one of the communications partners is authorized to send data. Both communications partners must therefore agree on how to alternate between send and receive (possibly depending on the DC system).

Process flow

The program, which builds the conversation, has send authorization at first. It can call the following functions:

Send Data

Return the send authorization and wait for data from the partner

Close the connection

By calling the receive command, you can pass the send authorization to the partner program, for example, to request an acknowledgement. The receiving program should therefore always check whether it has received the send authorization (see parameter STATUSINFO under COMMUNICATION RECEIVE: Receive Data).