84 Rockwell Automation Publication ICSTT-RM406J-EN-P - February 2021
B
backplane clip A sprung, plastic device to hold together two adjacent AADvance base units.
Part number 9904. Used in pairs.
base unit One of two designs which form the supporting parts of an AADvance
controller. See 'I/O base unit' and 'processor base unit'.
bindings Bindings describe a "relationship" between variables in different AADvance
controllers. Once a variable is "bound" to another variable, a unique and strong
relationships is created between the two variables and the SIL 3 Certified
SNCP protocol is used to verify that the consuming variable is updated with
the data from the producing variable.
black channel A communication path whose layer (i.e. cabling, connections, media
converters, routers/switches and associated firmware/software, etc.) has no
requirement to maintain the integrity of safety critical data transferred over it.
Measures to detect and compensate for any errors introduced into the black
channel must be implemented by the safety critical sender and receiver (by
software and/or hardware means) to make sure the data retains its integrity.
blanking cover A plastic moulding to hide an unused slot in an AADvance base unit.
boolean A type of variable that can accept only the values 'true' and 'false'.
BPCS Basic process control system. A system which responds to input signals and
generates output signals causing a process and associated equipment to
operate in a desired manner, but which does not perform any safety
instrumented functions with a claimed safety integrity level of 1 or higher.
Refer to IEC 61511 or to ANSI/ISA—84.00.01—2004 Part 1 (IEC 61511-1 Mod) for
a formal definition.
Equivalent to the Process Control System (PCS) defined by IEC 61508.
breakdown voltage The maximum voltage (AC or DC) that can be continuously applied between
isolated circuits without a breakdown occurring.
BS EN 54 A standard for fire detection and fire alarm systems.
BS EN 60204 A standard for the electrical equipment of machines, which promotes the
safety of persons and property, consistency of control response and ease of
maintenance.
bus A group of conductors which carry related data. Typically allocated to address,
data and control functions in a microprocessor-based system.
bus arbitration A mechanism for deciding which device has control of a bus.
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