AP4119 Rail Tag Programmer User Guide
TransCore Proprietary
2–16
AAR Tag Programming
This section applies to AAR-compliant tag programming, with the permissions tag settings as required to
support AAR-compliant tag programming. AAR-compliant programming requires validation and evaluation
of some of the incoming data.
AAR User Data Type Detection and Format Delimiting
The AP4119 tag programmer supports two basic AAR programming modes:
• Programming of rail tag as an AAR-compliant rail tag, or
• Programming of rail tag as an ASCII tag, according to the AAR Standard for Automatic Equipment
Identification (S-918) definition
The programmer evaluates the incoming data as being in one of the two programming mode categories,
or responds with an error condition and prevents improper tag programming. Upon receiving a legacy
AP4118 Tag Programmer-compatible command, the tag programmer evaluates the incoming user data
to determine the data format code (DFC) value as specified in AAR Specification S-918. Table 3 lists the
supported DFC values.
If the DFC is any value not listed in Table 3, the AP4119 creates an error condition and #Error response,
and tag programming stops.
Table 3 Data format code, AP4119 handling
6-Bit
Binary DFC
Value
Value Definition
(per AAR Standard S-918)
AP4119 Handling
000000 6-bit ASCII format
Allow programming: security character
enforcement required. Tag type handling not
required.
110011
AAR-compliant: other; non-
dynamic, non-passive alarm; AAR/
ATA/ISO
Allow programming: enforce tag type and
security characters. (This is the predominant DFC
value for a rail tag.)
110100 AAR rail: toll road
Allow programming: enforce tag type and
security characters
AAR Rail Tag Security Character Handling
Upon receiving a legacy AP4118-compatible tag programming command, the AP4119 programmer checks
the incoming security characters embedded in the user data. If the incoming characters are secure, the
AP4119 programmer then checks the secure characters against the security characters in the permissions
tag. The data remains the same if a match is made; otherwise an immediate data compare error occurs.
This error is due to security characters being replaced by space characters.
Non-secure characters can be written to the tag without look-up or comparison. Regardless of the
incoming programming command format (6-bit or 4-bit), the security characters reside in bits 106 through
117 of the actual tag ATA frame data. The AP4119 programmer treats the security field as two 6-bit
characters. Refer to “Table 10 6-Bit ASCII Codes” on page C–34 for the entire 6-bit ASCII character set.
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