Allen-Bradley DeviceNet 1784-PCIDS, Руководство пользователя, Страница: 20 / 101

Publication 1784-6.5.30 - February 2001
1-6 Before You Begin
Communicating with Your
Host Application
Your host application communicates with the scanner via input and
output image tables. Input data, gathered from the network’s
devices, is organized within the scanner and made available for the
host application to “read” from the input image table.
The scanner does not send data to your host application. Data
transferred between the scanner and the host application must be
initiated by the host application.
Output data is sent, or “written,” to
the scanner by your host application by placing the data in the output
image table. This data is organized in the scanner, which in turn
passes the data on to your scanned devices via strobe, poll, change of
state, or cyclic messages.
Host Application
1784-PCIDS Card
B
A1
C
D
A2
E
E
X
Y
Y
Z
Y
Y
C
D
A2
Z
Y
Y
Y
Y
Input/Output Data File
E
E
Internal Input
Data Storage
I/O Map
Input from
the devices
Internal Output
Data Storage
I/O Map
Data
Transfer
Write
Data
Transfer
Read
Output to
the devices