Structured Text; Serial_Port_Control Structure - Allen-Bradley Logix5000 Reference Manual

AWT(Channel,Source,
SerialPortControl);
Mnemonic Data Type
.EN BOOL
.EU BOOL
.DN BOOL
.RN BOOL
.EM BOOL
.ER BOOL
.FD BOOL
.LEN DINT
.POS DINT
.ERROR DINT
Description:
ASCII Serial Port Instructions (ABL, ACB, ACL, AHL, ARD, ARL, AWA, AWT)

Structured Text

The operands are the same as those for the relay ladder AWT instruction.
However, you specify the Serial Port Control Length and the Characters Sent
values by accessing the .LEN and .POS members of the
SERIAL_PORT_CONTROL structure, rather than by including the values in
the operand list.

SERIAL_PORT_CONTROL Structure

Description
The enable bit indicates that the instruction is enabled.
The queue bit indicates that the instruction entered the ASCII queue.
The done bit indicates when the instruction is done, but it is asynchronous to the logic scan.
The run bit indicates that the instruction is executing.
The empty bit indicates that the instruction is done, but it is synchronous to the logic scan.
The error bit indicates when the instruction fails (errors).
The found bit does not apply to this instruction.
The length indicates the number of characters to send.
The position displays the number of characters that were sent.
The error contains a hexadecimal value that identifies the cause of an error.
The AWT instruction sends the specified number of characters (Serial Port
Control Length) of the Source tag to the device that is connected to the serial
port of the controller.
Follow these guidelines to program the AWT instruction.
1. Configure the serial port of the controller.
If your application
Uses ARD or ARL instructions
Does not use ARD or ARL instructions Select either System or User mode
2. This is a transitional instruction.
· In relay ladder, toggle the rung-condition-in from cleared to set each
time the instruction should execute.
· In structured text, condition the instruction so that it executes only on a
transition.
Rockwell Automation Publication 1756-RM003N-EN-P - October 2011
Then
Select User mode
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