IAI America XSEL-S - Manual (Page 34)

Chapter 3 Operation (Construction for Network)
28
IA Net
XSEL-R/S
3.1.2 Occupied Area in Shared Memory
In the shared memory, there is a area equivalent to 256 words in total. The shared word
numbers from No. 0 to 255 are given to every word (16 bits) unit. Also every four words denotes
one station and each station unit is identified with the station numbers from No. 0 to 63.
The construction of the network has to have 64 (Station No. 0 to 63) total stations, or less.
Each XSEL controller occupies from one up to four station(s) and an extension I/O unit
occupies four stations.
Therefore, 64 units can be connected if IA Net network is constructed with only XSEL
controllers and all of them occupying one station each. If connecting an extension I/O unit or a
unit of XSEL controller that occupies two or more stations, the number of connectable units will
reduce according to the number of stations.
The number of the stations to be occupied by XSEL is to be set in the parameter. [Refer to 3.2
Shared Memory Assignments]
Image of Occupied Areas
Shared Memory Area
Shared Word
No.
0 1 2 3 4 5 6 7 8 9 10 11 ·· 252 253 254 255
Station No. 0 1 2 ·· 63
··
Caution Duplicate station number settings are not permitted.
If duplication is made, “Error No. 211/552 IA Net Link Error” will occur
and communication becomes unavailable.
Be careful not to duplicate station number assignments. When an XSEL
controller or an extension I/O unit is configured to occupy more than
one station, be sure that other XSEL controllers are not also configured
to occupy the same stations (overlapping stations).
Example: There is duplication
between Unit A and Unit B in
Station No. 1.
Because Unit A occupies two
stations, the station number for
Unit B should be 2. If Station 2
was accidentally assigned station
number 1, both Unit A and unit B
(as shown) would both be
attempting to occupy station 1.
Unit A is configured for two
stations, therefore, it occupies
stations 0 and 1. Unit B is also
configured for two stations, and it
occupies stations 2 and 3.
XSEL 1st Unit
(1 station occupied)
XSEL 2nd Unit
(2 stations occupied)
XSEL nth Unit
(1 station occupied)
Station
No.0
Station No.0
Unit A
(2 stations to be occupied)
Unit B
(2 stations to be occupied)
Station No.1
Station
No.1
Station
No.2