example based on: https://developer.community.boschrexroth.com/t5/ctrlX-PLC/USB-RS232-adapter/m-p/54609
see forum: https://developer.community.boschrexroth.com/t5/ctrlX-PLC/USB-serial-communication-via-USB-C-USB-A-adapter-dev-ttyACM0/m-p/73146/highlight/true#M900
see forum: https://developer.community.boschrexroth.com/t5/ctrlX-PLC/Edit-plc-system-cfg-Connect-Barcode-Scanner-to-PLC-project/m-p/77072 STRING (one character) generated STRING for loop indexCASE iState OF
0:
(* Code erhalten am 12.06.2023. Damit ist es nun möglich, auch ttyACM-Devices am USB zu nutzen. Erfolgreich getestet am 13.06.2023 *)
(* Diese Sequenz 0 muss einmalige ausgeführt werden und anschliessend muss ein Reboot durchgeführt werden *)
IF bExe_WriteNewConfig THEN
udiResultConfig := SettgSetStringValue(pszComponent:='SysCom', pszKey:='Linux.DeviceFile', pszValue:='/dev/ttyACM', iLen:=11);
IF (udiResultConfig <> 0) THEN
bErrorConfig := TRUE;
ELSE
bDoneConfig := TRUE;
END_IF
bExe_WriteNewConfig := FALSE;
ELSIF bStartCom
AND NOT bDoneComOpen THEN
(* next step, open com port *)
iState:= 1;
END_IF
1:
IF bInitComSettings THEN
(* Com settings *)
settings.sPort := SYS_COMPORT1;
settings.ulBaudrate := SYS_BR_115200;
settings.byParity := SYS_NOPARITY;
settings.byStopBits := SYS_ONESTOPBIT;
bInitComSettings := FALSE;
END_IF
(* Com open *)
handle := Syscom.SysComOpen2(
pSettings:= ADR(settings),
pSettingsEx:= 0,
pResult:= ADR(result));
IF (udiResultComOpen <> 0) THEN
bErrorComOpen := TRUE;
ELSE
bDoneComOpen := TRUE;
iState:= 2;
END_IF
2:
(* Com read *)
udiReturn := Syscom.SysComRead(
hCom := handle,
pbyBuffer := ADR(arByte),
ulSize := SIZEOF(arByte),
ulTimeout := 0,
pResult := ADR(result));
sStringFinished := ''; // clear STRING
FOR iIdx:=0 TO 29 BY 1 DO
sChar[0] := arByte[iIdx]; // get ASCII from BYTE-buffer and save one character
sStringFinished := CONCAT(sStringFinished, sChar); // build the whole STRING
END_FOR
IF udiReturn <> 0 THEN
udiLastReceivedNumberOfBytes := udiReturn;
END_IF
bComReadCyclicActive := TRUE;
END_CASE
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