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Section XXIV ISaGRAF Function and Function Blocks 635 Read Data From a Socket -- SockRead() Type C Function Block Function Read data from an established connection FBD Syntax SockRead( DINT SOCK, DINT MAX ) SockRead.rslt SockRead.size SockRead.data Parameters sock: DINT connection to read data from. max: DINT maximum number of byte to read from connection. Return Values rslt: DINT -2 = invalid max SIZE (must be <= 255) or invalid SOCK. -1 = no connection established. 0 = success (data available). 1 = blocked (no data available). data: DINT data bytes read (STRING). size: DINT number of data bytes read. Remarks Read data from an established socket and place it in the DATA output string. SockConnect or SockListen should be called and the status checked before every read and write of the socket. If using SockConnect in structured text, you must declare a function block instance in the ISaGRAF dictionary.
