String (St) Data File - Allen-Bradley MicroLogix 1400 Instruction Manual

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364 ASCII Instructions

String (ST) Data File

Publication 1766-RM001A-EN-P - October 2008
See on page 624 for the ASCII parameters that you set via the Channel 0
configuration screens in your programming software. Configuration of the
two append characters for the AWA instruction can be found in the
General tab of Channel Configuration option in RSLogix 500/RSLogix
Micro.
Using ASCII Instructions with DFI Full-Duplex
However, you can use the AWA and AWT instructions with DF1
Full-Duplex protocol. This functionality is provided for backward
compatibility with the legacy devices which are configured for DF1
Full-Duplex protocol to receive ASCII data from a controller.
When the channel is configured for DF1 Full-Duplex protocol, the AWA
and AWT instructions only are valid and can transmit an ASCII string out
of the RS-232 port. If the RS-232 port is configured for any protocol other
than DFI Full-Duplex and ASCII, the AWA and AWT instructions will error
out with an error code of 9.
DF1 Full-Duplex packets take precedence over ASCII strings, so if an
AWA or AWT instruction is triggered while a DF1 Full-Duplex packet is
being transmitted, the ASCII instruction will error out with an error code
of 5.
See on page 592 for the DF1 Full-Duplex protocol parameters that you
set via the Channel 0 configuration screens in your programming
software. Configuration of the two append characters for the AWA
instruction can be found in the General tab of Channel Configuration
option in RSLogix 500/RSLogix Micro.
File Description
The string data file is used by the ASCII instructions to store ASCII
character data. The ASCII data can be accessed by the source and
destination operands in the ASCII instructions. The string data file can also
be used by the copy (COP) and move (MOV, MVM) instructions.
String files consist of 42-word elements. One string file element is shown
below. You can have up to 256 of these elements in the string file.