Allen-Bradley MicroLogix 1100 Instruction Set Reference Manual

Publication 1763-RM001C-EN-P - October 2009
310 ASCII Instructions
Instruction Types and
Operation
There are two types of ASCII instructions, ASCII string control and ASCII
port control. The string control instruction type is used for manipulating
data and executes immediately. The port control instruction type is used
for transmitting data and makes use of the ASCII queue. More details are
provided below.
ASCII String Control
These instructions are used to manipulate string data. When a string
control instruction is encountered in a ladder logic program, it executes
immediately. It is never sent to the ASCII queue to wait for execution. The
following table lists the ASCII string control instructions used by the
MicroLogix 1100 controllers:
ASCII Port Control
These instructions use or alter the communication channel for receiving or
transmitting data. The following table lists the ASCII port control
instructions used by the MicroLogix 1100 controllers:
When the ACL (ASCII Clear Buffer) instruction is encountered in a ladder
logic program, it executes immediately and causes all instructions to be
removed from the ASCII queue, including stopping execution of the ASCII
instruction currently executing. The ER (error) bit is set for each
instruction that is removed from the ASCII queue.
When any of the other port control instructions are encountered in a
ladder logic program, it may or may not execute immediately depending
on the contents of the ASCII queue. The ASCII queue is a FIFO (first-in,
first-out) queue which can contain up to 16 instructions. The ASCII queue
operates as follows:
• When the instruction is encountered on a rung and the ASCII queue
is empty, the instruction executes immediately. It may take several
program scans for the instruction to complete.
MicroLogix 1100
ACI (String to Integer) AIC (Integer to String)
ACN (String Concatenate) ASC (String Search)
AEX (String Extract) ASR (ASCII String Compare)
MicroLogix 1100
ABL (Test Buffer for Line) ARD (ASCII Read Characters)
ACB (Number of Characters in Buffer) ARL (ASCII Read Line)
ACL (ASCII Clear Buffer) AWA (ASCII Write with Append)
AHL (ASCII Handshake Lines) AWT (ASCII Write)
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Allen-Bradley MicroLogix 1100 Specifications

General

Brand	Allen-Bradley
Model	MicroLogix 1100
Category	Controller
Language	English