Rockwell Automation 1791DS-IBxxxx Guard I/O DeviceNet Safety Modules - Manual (Page 11)

Rockwell Automation Publication 1791DS-UM001J-EN-P - May 2013 11
Preface
Terminology Refer to the table for the meaning of common terms.
Term Meaning
Bus off Indicates a status of very high error-count occurrence on a communication cable. A bus off error is detected when the internal error counter counts more
errors than the predetermined threshold value. (The error counter returns to zero when the master is started or restarted.)
Connection Logical communication channel for communication between nodes. Connections are maintained and controlled between masters and slaves.
CRTL Connection reaction time limit.
DeviceNet safety An implementation of a safety protocol on a standard DeviceNet network.
EDS Acronym for electronic data sheet, a template that RSNetWorx for DeviceNet software uses to display the configuration parameters, I/O data profile, and
connection-type support for a given DeviceNet safety module. These are text files used by RSNetWorx for DeviceNet software to identify products and
commission them on a network.
L- Output +24V DC common.
M Sinking output common channel, output switches to the common voltage.
MTBF Acronym for mean time between failure, the average time between failure occurrences.
ODVA Acronym for Open DeviceNet Vendor Association, a nonprofit association of vendors established for the promotion of DeviceNet networks.
P Sourcing output channel, output switches to the plus voltage.
PFD Acronym for probability of failure on demand, the average probability of a system to fail to perform its design function on demand.
PFH Acronym for probability of failure per hour, the probability of a system to have a dangerous failure occur per hour.
Proof test Periodic test performed to detect failures in a safety-related system so that, if necessary, the system can be restored to an as-new condition or as close as
practical to this condition.
S+ Output +24V DC.
SNN Acronym for safety network number, which uniquely identifies a network across all networks in the safety system. You are responsible for assigning a
unique number for each safety network or safety sub-net within a system.
Standard Devices or portions of devices that do not participate in the safety function.