Rockwell Automation 20-COMM-R Remote I/O Adapter - Manual (Page 115)

20-COMM-R Remote I/O Adapter User Manual
Publication 20COMM-UM004D-EN-P
Glossary
A Adapter
Devices such as drives, controllers, and computers usually require a
network communication adapter to provide a communication interface
between them and a network such as Remote I/O. An adapter reads data on
the network and transmits it to the connected device. It also reads data in the
device and transmits it to the network.
The 20-COMM-R Remote I/O adapter connects PowerFlex 7-Class drives
to a Remote I/O network. Adapters are sometimes also called ‘cards’,
‘embedded communication options’, ‘gateways’, ‘modules’, or
‘peripherals’.
B
Baud Rate
A unit of signaling speed equal to the number of discrete conditions or
signal events per second. Remote I/O networks support baud rates of 57.6
Kbps, 115.2 Kbps, or 230.4 Kbps. The baud rate that you use on a network
depends on cable length. See
Selecting Remote I/O Cables on page 2-1 for
information on cables.
Block Transfer Messages
A block transfer message is a data transfer mechanism that allows transfers
of large amounts of data. The 20-COMM-R Remote I/O adapter uses Block
Transfer for two types of data.
Block Transfers that are 18 words or less in length are used to transfer I/O
data such as Reference/Feedback and Datalink values. These Block
Transfers are often referred to as ‘Block Transfer I/O’.
Block Transfers that are 20, 30, or 60 words in length are used to transfer
Explicit Messages that can access parameters and other data in a DPI device
such as a PowerFlex drive. These Block Transfers are often referred to as
Block Transfer Messaging. Block Transfer Messaging is often used to read
and write several parameters per Explicit Message using the ‘Get Attributes
Scattered’ and ‘Set Attributes Scattered’ services.
A Block Transfer Read (BTR) is initiated by the controller and contains no
data. The target device sends data in response to this request.
A Block Transfer Write (BTW) is initiated by the controller and contains
data for the target device. The target device only acknowledges the
successful receipt of the data.
C CAN (Controller Area Network)
CAN is a serial bus protocol on which DPI is based.
Size in Words Purpose See
18 or fewer I/O Chapter 4 , Using Discrete and Block Transfer I/O
20, 30, or 60 Explicit Messaging Chapter 5 , Using Block Transfer Messaging