Installation guide

86 DC 900-1564A
Synchronous Link Control (SLC) Programmer’s Guide
DLI_PROT_SEND_PRIOR_DATA command allows iProtModifier field values of
SLC_AML_A_PD through SLC_AML_G_PD for all message lengths, and restricts
SLC_AML_H_PD_SBM to single block messages.
The client application cannot send Link Control Blocks directly. However, the client can
use the
DLI_PROT_CONTROL command to request transmission of an SLC Link Control
Block that contains a STOP flow or RESUME flow request. Furthermore, the
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).
6.4.2.1 Low-level Network Message Structure
Figure 6–1 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 low-level network ser-
vice. This structure is also defined within the
slc_blks.h “C” include file.
Note that transmission sequence identifier and message block identifier fields do not
appear within this message structure definition. The SLC protocol service on the ICP
handles these two requirements automatically as it provides message-blocking support.
typedef struct user_low_level_message_struct
{
UINT8 lci;
/* Optional ACI (and extension) inserted here
REPLACE first few "info" field characters. */
UINT8 info [CONSTANT_MAX_LO_NET_INFO_BLOCK];
} USER_LOW_LEVEL_MESSAGE_TYPE;
Figure 6–1: Low-level Network Message Header Structure