Omron CJ - PROGRAMMING MANUAL 08-2008 Programming Manual page 344

Serial Communications
System Configuration
Note
Data Refresh Methods
Complete Link Method
Polling Unit Link Method
306
CPU Unit
Polling Unit
RS-422/485
CJ1W-CIF11
RS-422A
Converter
(See
note 1.)
CPU Unit CPU Unit
Polled Unit No. 0 Polled Unit No. 1
Number of Polled Units: 8 max.
(See note 2.)
1. The CJ1W-CIF11 is not insulated and the total transmission distance is 50
meters max. If the total transmission distance is greater than 50 meters,
use the insulated NT-AL001 and do not use the CJ1W-CIF11. If only the
NT-AL001 is used, the total transmission distance can is 500 meters max.
2. Up to 8 Units, including the PT and Polled Units, can be connected to the
Polling Unit when a PT set for Serial PLC Link communications is on the
same network.
The following two methods can be used to refresh data.
• Complete link method
• Polling Unit link method
The data from all nodes in the Serial PLC Links are reflected in both the Poll-
ing Unit and the Polled Units. (The only exceptions are the address allocated
to the connected PT's unit number and the addresses of Polled Units that are
not present in the network. These data areas are undefined in all nodes.)
Example: Complete link method, highest unit number: 3.
In the following diagram, Polled Unit No. 2 is either a PT or is a Unit not
present in the network, so the area allocated for Polled Unit No. 2 is undefined
in all nodes.
Polling Unit Polled Unit No.0
Local area Polling Unit
Polled Unit
Local area
No.0
Polled Unit Polled Unit
No.1 No.1
Undefined Undefined
Polled Unit Polled Unit
No.3 No.3
(Not used) (Not used)
(Not used) (Not used)
(Not used) (Not used)
(Not used) (Not used)
The data for all the Polled Units in the Serial PLC Links ar reflected in the Poll-
ing Unit only, and each Polled Unit reflects the data of the Polling Unit only.
The advantage of the Polling Unit link method is that the address allocated for
the local Polled Unit data is the same in each Polled Unit, allowing data to be
CPU Unit
PT
Unit No. 2
Polled Unit No. 3
NS-AL002 when using
an NS-series PT
Polled Unit No.1
Polling Unit
Polled Unit
No.0
Local area
Undefined
Polled Unit
No.3
(Not used)
(Not used)
(Not used)
(Not used)
Section 6-3
CPU Unit
Polling Unit
RS-232C
CPU Unit
OR
Polled Unit No. 0
Polled Unit No.3
Polling Unit
Polled Unit
No.0
Polled Unit
No.1
Undefined
Local area
(Not used)
(Not used)
(Not used)
(Not used)