Logix5000 Controllers General Instructions - SLAC Confluence

602 ASCII Serial Port Instructions (ABL, ACB, ACL, AHL, ARD, ARL, AWA, AWT)Arithmetic Status Flags:Fault Conditions:not affectednoneExecution:Condition Relay Ladder Action Structured Text Actionprescan The rung-condition-out is set to false. No action taken.rung-condition-in is false The rung-condition-out is set to false. narung-condition-in is true The instruction executes when rung-condition-intoggles from cleared to set.naThe rung-condition-out is set to true.EnableIn is set na EnableIn is always set.instruction executionThe instruction executes.The instruction sends a specified number of characters.The .EN bit is set.The remaining status bits, except .UL, are cleared.The instruction attempts to enter the ASCII queue.postscan The rung-condition-out is set to false. No action taken.Example 1:When the temperature reaches the low limit (temp_low is set), theAWT instruction sends a message to the MessageView terminal that isconnected to the serial port of the controller. The message containsnine characters from the DATA member of the string[2] tag, which is astring. (The $14 counts as one character. It is the hex code for theCtrl-T character.) The last character is a carriage return ($r), whichmarks the end of the message.Relay Laddertemp_lowAWTASCII WriteChannel 0Sourcestring[2]'$142224\01$r'SerialPort Control temp_low_writeSerialPort Control Length 9Characters Sent 9ENDNERPublication 1756-RM003I-EN-P - January 2007