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Chapter 8 Exercising program
8-10
[Figure 8.5] describes TX/RX data path according to data TX/RX map in [Table 8.3] with the example of Cnet
stations 1 & 4 and monitoring device. Cnet stations 2 & 3 are the same case as in communication via the identical
path. Direct communication between monitoring device and station 4 on mobile body is unavailable in the figure,
thus, data will be changed through station 1. As shown in [Figure 8.4], 20 bytes from %MB0 of station 1 is the
saving area of data read from station 4 of mobile body, and via this area monitoring device starts reading data of
station 4. To the contrary, when data is written from monitoring device to station 4, 50 bytes data is written
from %MB100 address of station 1 and 10 bytes data of 50 bytes starting from %MB140 address is re-transmitted
to station 4 to change data between monitoring device and station 4.
1) Optical modem connection
Connect 9-pin cable with Cnet stations 1,2,3 and optical modem via RS-232C channel. Since optical modem
connection is same as in dedicated modem, refer to 4.4 How to connect to modem for connection between
Cnet I/F module and dedicated modem. Optical modem on mobile body is connected with Cnet I/F module
station 4 via RS-422 cable, thus, use optical modem which supports RS-422 communication for connection in
accordance with RS-422’s standard connection method.
2) Setting of basic parameters
Identical basic parameters shall be set in RS-422 channel of Cnet stations 1,2,3 for communication with
monitoring device, and RS-232C channel shall be set to dedicated modem mode in operation of user mode to
operate as a communication master station of Cnet station 4. [Table 8.4] describes setting items of Cnet I/F
module for this. Set operation mode switch as specified in the table and prepare basic parameters through
Frame Editor to download to Cnet I/F module and then to complete basic setting.
[Table 8.4] Setting items of Cnet I/F module
Setting item
Cnet on fixed body
Cnet on mobile body
Remark
Operation mode switch
‘4’
‘3’
Operation mode
User defined
communication
[Note]
Station No.
Basic value(Not used)
Communication
speed
19200bps
RS-232C
Data/Stop Data-8/Start-1/Stop-1
Not used
Parameters in
RS-232C
channel of Cnet
stations 1,2,3
shall be set
identical.