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Glossary
Term Definition
assembly Internal data in a device gathered as one group to be accessed externally.
Busoff Status that occurs when the error rate is extremely high over a communica-
tions cable.
An error is detected when the internal error counter exceeds a certain thresh-
old value.
(The internal error counter is cleared when the Master is started or restarted,
and it is decremented when a normal frame is received.)
configuration The settings for a device and a network.
connection A logical communications path used to communicate between devices.
DeviceNet Safety A safety network that adds a safety protocol to DeviceNet to comply with up to
SIL3 according to IEC61508, up to Safety Category 4 according to EN954-1.
discrepancy time The time period from a change in one of two inputs until the other input
changes.
dual channel Using two inputs or outputs as the input or output for redundancy.
Dual Channel Complementary Setting to evaluate that two logic states are complementary.
Dual Channel Equivalent Setting to evaluate that two logic states are equivalent.
EPI The interval of safety data communications between the Safety Master and the
Safety Slave.
error latch time The time period to hold an error state (control data, status data, and LED indi-
cations).
Fault Present Several function blocks have Fault Present as an optional output. This is an
error output that indicates that the applicable function block has detected an
internal logic error or an input data timing error.
multi-cast connection Safety I/O communications in a 1:n configuration (n = 1 to 15).
open type The open method for Safety Connection. One of three types is selected in the
settings of a connection to the Safety Master.
PFD Probability of Failure on Demand
Shows the average failure rate for a system or device demand. Used for calcu-
lating the SIL (Safety Integrity Level) for a safety system.
PFH Probability of Failure per Hour
Shows the failure rate per hour for a system or device. Used for calculating the
SIL (Safety Integrity Level) for a safety system.
safety chain The logical chain to actualize a safety function, that consists of the input device
(sensor), the control device (including a remote I/O device), and the output
device (actuator).
safety controller (safety PLC) A controller with high reliability used for the safety control.
safety data Extremely reliable data, with risk reduced to a permissible level.
safety protocol The communications hierarchy added to actualize highly reliable communica-
tions.
safety signature A certificate of the configuration data issued to a device from the Network Con-
figurator. The device verifies that the configuration data is correct by using the
safety signature.
single channel Using only one input or output as the input or output.
single-cast connection Safety I/O communications in 1:1 configuration.
standard A device or device function to which safety measures are not applied.
test pulse A signal used to detect external wiring coming into contact with the power sup-
ply (positive) or short circuits between signal lines.
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