Logix5000 Controllers General Instructions - SLAC Confluence

584 ASCII Serial Port Instructions (ABL, ACB, ACL, AHL, ARD, ARL, AWA, AWT)SERIAL_PORT_CONTROL StructureMnemonic Data Type Description.EN BOOL The enable bit indicates that the instruction is enabled..EU BOOL The queue bit indicates that the instruction entered the ASCII queue..DN BOOL The done bit indicates when the instruction is done, but it is asynchronous to the logic scan..RN BOOL The run bit indicates that the instruction is executing..EM BOOL The empty bit indicates that the instruction is done, but it is synchronous to the logic scan..ER BOOL The error bit indicates when the instruction fails (errors)..FD BOOL The found bit does not apply to this instruction..POS DINT The position stores the status of the control lines..ERROR DINT The error contains a hexadecimal value that identifies the cause of an error.Description:The AHL instruction can:• obtain the status of the control lines of the serial port• turn on or off the data terminal ready (DTR) signal• turn on or off the request to send signal (RTS)To program the AHL instruction, follow these guidelines:1. Configure the serial port of the controller:If Your Applicationuses ARD or ARL instructionsdoes not use ARD or ARLinstructionsThenSelect User modeSelect either System or User mode2. Use the following table to select the correct values for theANDMask and ORMask operands:To Turn DTR And Turn RTS: Enter ThisANDMask Valueoff off 3 0on 1 2unchanged 1 0on off 2 1on 0 3unchanged 0 1unchanged off 2 0on 0 2unchanged 0 0And Enter ThisORMask ValuePublication 1756-RM003I-EN-P - January 2007