====== Reading data from a port ====== {{:en:mervis-ide:35-help:readport.png}} ===== Function name ===== READPORT ===== Function ===== Function readport reads data from a given communication port. ===== Inputs ===== |Input |Type |Description | |DATA |BYTE_PTR |TBD | |HANDLE |IO.COMMHANDLE|Parameters of the running communication| |MAXLENGTH|INT |Maximum data length | ===== Outputs ===== |Output|Type|Description | |=> |INT |Output:\\ 0...Data **not received**\\ 1...Data **received**| ===== Example of a ST call: ===== PROGRAM main (program's body) var def : string; handle : io.commhandle; state : int := 0; data : array[0..31] of byte; dataRecv : array[0..31] of byte; received : int; end_var case state of 0: (*def := 'tcp:192.168.1.4:7';*) (*def := 'udp:192.168.1.4:7';*) def := 'serial:10:9600,8,N,1'; handle := io.openport(def); if handle >= 0 then state := 1; end_if; 1: if io.getportstatus(handle) = 0 then (* OperationStatus_Ok *) (* connection established *) data[0] := 5; data[1] := 10; data[2] := 6; data[3] := 11; if io.writeport(handle, adr data[0], 10) then state := 2; end_if; end_if; 2: if io.getportstatus(handle) = 0 then (* OperationStatus_Ok *) (* all data sent *) state := 3; end_if; 3: received := io.readport(handle, adr dataRecv[0], 20); if received > 0 then (* some data received *) io.closeport(handle); state := 4; else io.getportstatus(handle); end_if; else state := 4; end_case; END_PROGRAM