IAI America XSEL-S - Manual (Page 33)

Chapter 3 Operation (Construction for Network)
27
IA Net
XSEL-R/S
Chapter 3 Operation (Construction for Network)
3.1 Before Initial Setting
3.1.1 Writing to and Reading from Shared Memory
IA Net possesses a shared memory with 256 words that all the connected XSEL controllers can
write data to and read data from.
XSEL controllers and extension I/O units have the occupied domains in the shared memory.
They write (output) their own information (ON/OFF information in binary unit) to this shared
memory area, and thereby make the information available to other networked XSEL controllers.
Since all the XSEL controllers can read (input) the contents in the shared memory, operations
can be performed while exchanging information.
x Image of Shared Memory
XSEL
1st Unit
XSEL
2nd Unit
XSEL
3rd Unit
XSEL
Nth Unit
XSEL
4th Unit
An XSEL controller can read
input data from the entire
shared memory area; therefore,
it can monitor output data which
has been written from other
XSEL controllers.
An XSEL controller can
only write output data to
the shared memory area
that is occupies.
࡮
࡮
Extension I/O Unit
Writing
Reading
Shared Memory
XSEL 1st
Unit
Occupied
Area
XSEL 2nd
Unit
Occupied
Area
XSEL 3rd
Unit
Occupied
Area
XSEL 4th
Unit
Occupied
Area
Extension
I/O Unit
Occupied
Area
࡮
࡮
XSEL nth
Unit
Occupied
Area
࡮
࡮
Writing
Reading
Writing
Reading
Writing
Reading
Writing
Reading
Writing
Reading