578 Rockwell Automation Publication 1756-RM003N-EN-P - October 2011
Chapter 17 ASCII Serial Port Instructions (ABL, ACB, ACL, AHL, ARD, ARL, AWA, AWT)
ASCII Test For Buffer Line
(ABL)
The ABL instruction counts the characters in the buffer up to and including the
first termination character.
Operands:
Relay Ladder
Structured Text
The operands are the same as those for the relay ladder ABL instruction. You
access the Character Count value via the .POS member of the
SERIAL_PORT_CONTROL structure.
SERIAL_PORT_CONTROL Structure
Operand Type Format Description
Channel DINT Immediate
Tag
0
Serial Port
Control
SERIAL_PORT_
CONTROL
Tag Tag that controls the operation
Character
Count
DINT Immediate 0
During execution, displays the number of
characters in the buffer, including the first set
of termination characters.
EN
DN
ER
ASCII Test For Buffer Line
Channel ?
SerialPort Control ?
Character Count ?
ABL
ABL(Channel
SerialPortControl);
Mnemonic 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 the termination character or characters.
.POS DINT The position determines the number of characters in the buffer, up to and including the first set of
termination characters. The instruction only returns this number after it finds the termination character
or characters.
.ERROR DINT The error contains a hexadecimal value that identifies the cause of an error.
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