Installation guide

4: Commands and Responses
DC 900-1564A 43
Table 5–16 on page 75 lists symbolic names for the
DLI_PROT_SEND_NORM_DATA AML val-
ues that can appear in the
iProtModifier field for both writes and reads. The validity of
these values is influenced by both the network level and the message length. An AML for
a single-block message can be used only with a message that fits within a single trans-
mission block on the SLC network. However, an AML for a multi-block message can be
used for either a single-block message or a multi-block message.
The
DLI_PROT_SEND_NORM_DATA data content is variable. It contains selected SLC infor-
mation block header fields followed by the message information field. The SLC protocol
software supports a maximum message information field size of 4000 bytes for low-
level network messages or 3840 bytes for high-level network messages. For additional
information on data content, see Section 6.4.2 on page 85 and Section 6.4.3 on page 88.
4.3.3 Priority Data
DLI_PROT_SEND_PRIOR_DATA can be used only when SLC protocol service is configured.
It is not supported when SLC envelope service is configured. The header formats are
detailed in Section 5.13 on page 76.
DLI_PROT_SEND_PRIOR_DATA contains an entire SLC high-priority message. The applica-
tion writes this command to the ICP to transmit a high-priority message through the
WAN interface to the SLC network. The application reads this response when the ICP
reports a high-priority message received from the WAN interface to the SLC network.
After reading a
DLI_PROT_SEND_PRIOR_DATA response, the application extracts the
iProtModifier field value (the ICP message identifier consisting of the AML value and
AML descriptor), performs any required message protection operations, then using
same
iProtModifier field value writes the DLI_PROT_SAFE_STORE_ACK command to
acknowledge that the message has been stored safely. The ICP examines the
iProtModifier field, and if necessary, transmits a link control block with the corre-
sponding acknowledge message label on the specified SLC network connection.