Allen-Bradley DeviceNet 1784-PCIDS, User Manual, Page: 9 / 101

Publication 1784-6.5.30 - February 2001
About This User Manual P-5
Terminology
This term Means
Change of State A type of I/O data communication. The scanner module can send and
receive data with slave devices that have the change of state feature.
Data is sent either whenever a data change occurs, or at the rate of the
heartbeat if no data has changed.
Cyclic A type of I/O data communication. The scanner can send and receive data
with slave devices that have the cyclic feature. Data is only sent at a
user-configurable rate.
Dual Mode The scanner is in dual mode when it serves as a master to one or more
slaves and as a slave to another master simultaneously.
EDS Electronic Data Sheet. A vendor-supplied template that specifies how
information is displayed as well as what is an appropriate entry (value).
EPR Expected Packet Rate. One quarter of the time in milliseconds that the
scanner must wait to hear from a device before deciding the connection
has failed.
Explicit
Messaging Messaging protocol that states the meaning of the message. This
protocol commands the performance of a particular task and returns the
results of the task performance to the requestor. Used for lower priority
tasks, such as configuration and data monitoring.
Heartbeat Rate This only applies to change of state messaging.
Devices that are configured for change of state data also send a
“heartbeat” signal to indicate the device is still operating on the network
even if no data has changed.
Host Platform The computer in which the 1784-family scanner is installed.
I/O An abbreviation for “input and output.”
Implicit
Messaging The type of messaging used for high priority I/O control data; e.g., change
of state, cyclic, polled, or strobed.
Input Data Data produced by a DeviceNet device and collected by the scanner for a
host platform to read.
MAC ID The network address of a DeviceNet node.
Network The DeviceNet network or the RSNetWorx for DeviceNet software
representation of the network.
Node Hardware that is assigned a single address on the network (also referred
to as device).
Offline When the RSNetWorx is not communicating on the network.
Online When RSNetWorx is configured and enabled to communicate on the
network.
Output Data Data that is produced by a host application and written to the scanner’s
memory. This data is sent by the scanner to DeviceNet devices.
PC Abbreviation for an IBM
®
compatible personal-computer.
Polled A type of input/output-data communication. A polled message solicits a
response from a single, specified device on the network (a point-to-point
transfer of data).
Record The node address and channel-specific memory assigned in the scanner’s
non-volatile storage for a node in the scanlist.
Rx An abbreviation for “receive”.
Scanlist The list of devices (nodes) with which the scanner is configured to
exchange I/O data.
Scanner The function of the 1784-family scanner to support the exchange of I/O
with slave modules.
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