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Table 9 - Receive Data Format — Array Data Type
Byte 1
Byte 2
Receive Record Number
Status Byte
Table 10 - Receive Data Format — Short_String Data Type
Byte 1
Byte 2
Receive Record Number
Status Byte
Set Up and Use Delimiter Operation
When receiving data strings from your serial device, the ASCII module can
take advantage of both Start and Stop (End) delimiters. The Start Delimiter is
the start-of-string indicator and the End Delimiter is the end-of-string
indicator.
When you select Start Delimiter operation, you define a character that
prompts the ASCII module to start storing the incoming data string. All
characters up to this Start Delimiter (after the previous message was
completed) are ignored. Once the Start Delimiter is received, all characters are
stored until either the End Delimiter is received or the
Max_Receive_Char_Length is reached. Once the End Delimiter is reached, the
data string is updated and the ASCII module ignores all subsequent data until
the start delimiter is received again.
If either delimiter is used, you can also elect whether to include those
characters in the data string. If the start delimiter mode is set to Disabled, then
the ASCII module always adds data to the string.
Receive String Data Type
Receive String Data Type is the format of the data – Array, Short_String, or
String. Which one you choose depends on your application, and modifies the
format of the header field in the data string.
The Array data type does not have a length that is associated with it. It is
equivalent to specifying a length of zero using a String or Short_String data
type.
The Short_String data type is the default data type of the device. This suffices
for most applications. The Short_String data type value has only 1 byte of
length, and the rest of the data bytes are appended after the length.
The String data type value has 2 bytes of length. The String data type is useful
in communicating to some controllers or other devices that have a data file
made to handle this data type. The length is little-endian (low byte, high byte),
and the high-order byte is always set to zero. The ASCII module receives up to
128 bytes of information, so the extra byte, although required for this data type,
is always 0.
Byte 3
Reserved
Byte 3
Reserved
Rockwell Automation Publication 1734-UM009C-EN-P - August 2022
Byte 4
Byte 5-X
Reserved
ASCII Data (max 128 bytes)
Byte 4
Byte 5-X
Length
ASCII Data (max 128 bytes)
Chapter 3
Module Tag Definitions
Byte X+1 (Max = 132)
<CR> (Terminator)
Byte X+1 (Max = 132)
<CR> (Terminator)
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