Installation guide

6: Programming Considerations
DC 900-1564A 89
DLI_PROT_SAFE_STORE_ACK command causes the SLC protocol service to determine
whether to transmit a Link Control Block that contains a corresponding Acknowledge
Message Label (AML).
6.4.3.1 High-level Network Message Structure
Figure 6–2 shows the structure of message header information within the data field of
all
DLI_PROT_SEND_NORM_DATA and DLI_PROT_SEND_PRIOR_DATA commands and
responses when the SLC network connection is configured for high-level network ser-
vice. See also the
slc_blks.h “C” include file.
Note that transmission sequence identifier (TSI) and message block identifier (MBI)
fields do not appear within this message structure definition. The SLC protocol service
on the ICP handles TSI and MBI field requirements automatically as it provides mes-
sage-blocking support.
6.4.3.2 Link Characteristics Identifier (LCI)
The link characteristics identifier field is required in each SLC message sent or received
on a high-level SLC network. Shown as the
lci field in Figure 6–2, the LCI appears as
the first byte in the data area of each
DLI_PROT_SEND_NORM_DATA or
typedef struct user_high_level_message_struct
{
UINT8 lci;
UINT8 hex [2];
UINT8 hen [2];
UINT8 mci;
/* Optional ACI (and extension) inserted here
do NOT count as "info" field characters. */
UINT8 info [CONSTANT_MAX_HI_NET_INFO_BLOCK];
} USER_HIGH_LEVEL_MESSAGE_TYPE;
Figure 6–2: High-level Network Message Header Structure