Page Mode
CAN-CBM-DP
Software Manual Rev. 2.0
44
PROFIBUS-DP
PLC
Page 0: Setup
Page 0: Acknowledge of Setup
From Page 51: TxId-Configuration
Page 51: Acknowledge of TxId-Configuration
From Page 151: RxId-Configuration
Page 151: Acknowledge of RxId-Configuration
From Page 251: Tx-Data
From Page 251: Rx-Data
CAN
Gateway
P
LC
-C
ycl
es
Program Loop
S
ing
le
C
all
6.4 Mode of Operation
6.4.1 Overview
In order to provide more CAN identifiers than can be stored in a PROFIBUS telegram, a protocol-
controlled data exchange between PLC and gateway is necessary.
For the communication so-called
pages
are defined in which the parameters and data are exchanged.
On PLC side an input and an output area are reserved for the transmission of the pages.
After the system has been started a page with setup data is exchanged between PLC and gateway. In
the following pages the PLC transmits the configuration of the Tx- and Rx-identifiers. These pages
contain the identifier numbers used for the CAN, the number of bytes and information about the data
format.
Fig. 6.4.1:
Exchange of parameters and data in Page Mode (overview)
If the setup has been completed, data can be exchanged. With each PLC cycle an input and an output
page is transmitted. If more identifiers have to be provided than can be stored in a page, the following
identifiers will be handled in the following PLC cycles. With rising number of identifiers and depending
on the length of data to be transmitted per identifier, more PLC cycles are required, therefore, to
transmit all data. In order to keep the number of PLC cycles low, input and output page should be
selected as large as possible.