Installation guide

90 DC 900-1564A
Synchronous Link Control (SLC) Programmer’s Guide
DLI_PROT_SEND_PRIOR_DATA command or response. Table 6–3 shows the internal for-
mat of the
lci field. See also the slc_blks.h “C” include file.
6.4.3.3 High-level Designators (HEX and HEN)
High-level designators are required in each SLC message sent or received on a high-level
SLC network. These fields identify the high-level exit center (HEX) and the high-level
entry center (HEN) for the message. Shown as the
hex and hen fields in Figure 6–2 on
page 89, the HEX and HEN contain two bytes each, and immediately follow the LCI.
Coding of the
hex and hen fields forbids use of the control characters DLE (0x10), ETB
(0x17) or SYN (0x16), but is otherwise unrestricted. The SLC protocol service on the
ICP validates the coding of the
hex and hen fields, but otherwise ignores the content of
these fields.
Table 6–3: Link Characteristics Identifier (LCI) on High-level Networks
Link Characteristics Identifier (LCI) — One Character
LCI_BASE_VALUE Always set
LCI_PDM Possible Duplicate Message (PDM) when set
LCI_ACI_PRESENT Additional Characteristics Identifier (ACI) present when set
LCI_HLD_PRESENT Always set (High Level Designators HEX/HEN present)
LCI_PROTECTION_MASK Mask to isolate (&) or ignore (&~) Protection bit-field
LCI_FULL_PROTECTION Protection bit-field value
LCI_LIMITED_PROTECTION Protection bit-field value
LCI_NO_PROTECTION Protection bit-field value
LCI_END_TO_END_PROTECTION Protection bit-field value
LCI_LAST_BLOCK Always set (to indicate entire message present)