Specifications

Glossary
31004624 8/2009 157
S
SAP
service access point. The point at which the services of 1 communications layer, as
defined by the ISO OSI reference model, is made available to the next layer.
SCADA
supervisory control and data acquisition. Typically accomplished in industrial
settings by means of microcomputers.
SDO
service data object. In CAN-based networks, SDO messages are used by the
fieldbus master to access (read/write) the object directories of network nodes.
segment
A group of interconnected I/O and power modules on an Island bus. An Island must
have at least 1 segment and, depending on the type of NIM used, may have as many
as 7 segments. The first (leftmost) module in a segment needs to provide logic
power and Island bus communications to the I/O modules on its right. In the primary
or basic segment, that function is filled by a NIM. In an extension segment, that
function is filled by an STB XBE 1200 or an STB XBE 1300 BOS module.
SELV
safety extra low voltage. A secondary circuit designed and protected so that the
voltage between any 2 accessible parts (or between 1 accessible part and the PE
terminal for Class 1 equipment) does not exceed a specified value under normal
conditions or under single-fault conditions.
SIM
subscriber identification module. Originally intended for authenticating users of
mobile communications, SIMs now have multiple applications. In Advantys STB,
configuration data created or modified with the Advantys Configuration Software can
be stored on a SIM (referred to as the “removable memory card”) and then written
to the NIM’s Flash memory.