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PAD Message Set
Chapter 11
113
Command Native Fields:
Reply Native Fields:
EXT
FF
SSQ
SEL
06
EXT
FF
SSQ
SEL
86
SEL (Select) — This one-byte field specifies the message set within the
Native mode. For PAD command messages, the hexadecimal value in this
field is 06. For PAD reply messages, the hexadecimal value in this field is
86.
SSQ (Sub-Sequence Number) — This one-byte field is a reserved byte
in the 1779-KFM.
EXT (Extension) — This one-byte field blocks messages formatted for
Data Highway from being accepted on Data Highway II unless they are
properly reformatted. The hexadecimal value in this byte must always be
FF.
PAD Fields
Figure 11.1 shows the Native-mode PAD message packet format
including the PAD fields. The PAD fields are those header fields common
to all Native-mode PAD message transmissions. Here we describe these
PAD fields:
TNS
2 Bytes
USER
NODE
LINK
STS
STS (Status) — In a command packet, this one-byte field has a
hexadecimal value of 00. In a reply packet, this field indicates a
successful transaction completion with a value of 00, or indicates an error.
Error codes are listed in Appendix A.