Logix5000 Controllers General Instructions - SLAC Confluence

ASCII Serial Port Instructions (ABL, ACB, ACL, AHL, ARD, ARL, AWA, AWT) 601SERIAL_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..LEN DINT The length indicates the number of characters to send..POS DINT The position displays the number of characters that were sent..ERROR DINT The error contains a hexadecimal value that identifies the cause of an error.Description:The AWT instruction sends the specified number of characters (SerialPort Control Length) of the Source tag to the device that is connectedto the serial port of the controller.To program the AWT 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. This is a transitional instruction:• In relay ladder, toggle the rung-condition-in from cleared toset each time the instruction should execute.• In structured text, condition the instruction so that it onlyexecutes on a transition. See .3. Each time the instruction executes, do you always send the samenumber of characters?IfYesNoThenIn the Serial Port Control Length, enter the number of characters tosend.Before the instruction executes, move the LEN member of the Sourcetag to the LEN member of the Serial Port Control tag.Publication 1756-RM003I-EN-P - January 2007