Publication 1763-RM001C-EN-P - October 2009
320 ASCII Instructions
Programming AWT Instructions
When programming ASCII output instructions, always precede the ASCII
instruction with conditional logic that either detects when new data needs
to be sent or, send data on a time interval. If sent on a time interval, use
an interval of 0.5 second or greater.
This instruction executes on a true rung. Once started, if the rung goes
false, the instruction continues to completion. If you want to repeat this
instruction, the rung must transition from false-to-true.
When using this instruction you can also perform in-line indirection. See
page 336 for more information.
Entering Parameters
Enter the following parameters when programming this instruction:
• Channel is the number of the RS-232 port, Channel 0.
• Source is the string element you want to write.
• Control is the control data file. See page 313.
• String Length (.LEN) is the number of characters you want to write
from the source string (0 to 82). If you enter a 0, the entire string is
written. This is word 1 in the control data file.
• Characters Sent (.POS) is the number of characters that the
controller sends to an external device. This is word 2 in the control
data file. Characters Sent (.POS) is updated after all characters have
been transmitted.
The valid range for .POS is from 0 to 82. The number of characters
sent to the destination may be smaller or greater than the specified
String Length (.LEN) as described below:
– Characters Sent (.POS) may be smaller than String Length (.LEN)
if the length of the string sent is less than what was specified in
the String Length (.LEN) field.
IMPORTANT
Do not continuously generate streams of ASCII data out
of a communications port. If ASCII write instructions
execute continuously, you may not be able to re-establish
communications with RSLogix 500 when the controller is
placed into the RUN mode.
efesotomasyon.com - Allen Bradley,Rockwell,plc,servo,drive
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