Logix5000 Controllers General Instructions - SLAC Confluence

578 ASCII Serial Port Instructions (ABL, ACB, ACL, AHL, ARD, ARL, AWA, AWT)ASCII Chars in Buffer (ACB)The ACB instruction counts the characters in the buffer.Operands:ACBASCII Chars in BufferChannel ?SerialPort Control ?Character Count ?ENDNERRelay LadderOperand Type Format EnterChannel DINT immediate 0tagSerial Port SERIAL_PORT_ tag tag that controls the operationControlCharacterCountCONTROLDINT immediate 0During execution, displays the number ofcharacters in the buffer.ACB(ChannelSerialPortControl);Structured TextThe operands are the same as those for the relay ladderACB instruction. However, you specify the Character Count value byaccessing the .POS member of the SERIAL_PORT_CONTROL structure,rather than by including the value in the operand list.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 indicates that the instruction found a character..POS DINT The position determines the number of characters in the buffer, up to and including the firstset of termination characters..ERROR DINT The error contains a hexadecimal value that identifies the cause of an error.Publication 1756-RM003I-EN-P - January 2007