Omron K3HB, Техническое руководство пользователя

Страница: 97 / 147

7-2
Overview of Explicit Message Communications
Section 5-1
Expl
ic
it
M
essage
C
o
m
m
un
icat
ions
5-1 Overview of Explicit Message Communications
5-1-1 Explicit Message Communications
Explicit message communications is a communications protocol for sending
commands from the master as explicit messages, and receiving explicit mes-
sages as responses from the nodes that receive the commands.
Explicit messages can be sent from the master to the Digital Indicator to read
and write the K3HB-DRT Digital Indicator variable area, send operation com-
mands, and read and write various other DeviceNet functions supported by
the Digital Indicator.
Explicit message communications can be used to send and receive data that
is not allocated in the IN and OUT Areas due to word size restrictions, and
data that does not require the frequent refreshing used by the IN Area and
OUT Area.
Use either of the following two methods depending on the application.
Reading/Writing K3HB-DRT Variable Area Data and Sending Operation Commands
Send CompoWay/F communications commands to K3HB-DRT Digital Indica-
tors by embedding them in explicit messages.
Reading/Writing K3HB-DRT Maintenance Information
Send explicit messages specific to the DeviceNet-compatible Digital Indicator.
5-1-2 Explicit Message Types
The explicit messages sent to the Digital Indicator can be divided into two
types: messages in which CompoWay/F commands are embedded and mes-
sages specific to DeviceNet-compatible Digital Indicators.
Sending CompoWay/F Commands to the K3HB-DRT (Embedded in Explicit Messages)
The master can send CompoWay/F communications commands to the K3HB-
DRT Digital Indicator by sending them as explicit message data.
When DeviceNet-compatible Digital Indicators are used, the explicit mes-
sages are automatically converted to CompoWay/F communications com-
mands and sent to the K3HB-DRT Digital Indicator. The responses from the
Digital Indicator are converted into explicit messages and returned to the
master. CompoWay/F commands are used to read from and write to the
K3HB-DRT variable area and to execute operation commands.
CompoWay/F commands consist of binary commands and ASCII commands.
DeviceNet Master
CPU Unit
K3HB-DRT Digital Indicator
IOWR or
CMND
instruction
Explicit message sent to
DeviceNet-compatible
Digital Indicator
CompoWay/F communications
command sent to K3HB
Digital Indicator (embedded in
explicit message)