24
The same interface is used both for AC and DC I/O boards. The selection is done by a jumper
that must be set according to the type of I/O boards used. Naturally AC I/O can only be used
when constant supply of electricity is available.
Each interface in the system must have a unique address by which it will be recognized when
communicated by the CPU. The address switch must be set to the address selected for the
particular interface during the hardware definition which is part of the configuration process.
The addressing uses a binary coding as explained below:
There are 6 micro switches numbered 1,2,3,4,5,6. Each micro switch according to its ordinal
number represents a value between 1 and 32 as shown above. The address is calculated by
summing up the values of the micro switches that are in the ON position.
Appendix "A"
supplies
a conversion table from binary to decimal that shows the setting of the switches required for
each address.
The red LED
indicates the communication between the CPU and the interface. When the
communication functions properly, the red led will blink a short blink each second.
The yellow and green LEDs serve the I/O test mode. After pushing the test button, the interface
goes into the I/O test mode. The yellow LED tells us whether we are testing outputs or inputs.
During the outputs test yellow LED
will be constantly ON and then each output will be
opened and closed, each opening and closing will be indicated by a blink of the green LED
.
During the inputs test the yellow LED
will blink once per each input being tested and if a
closed contact is detected, the red led
will blink as well.
5.1.1
I/O expansion and Remote I/O
When having a large number of local Inputs or Outputs we have to take into consideration that
the
Motherboard
of the
DREAM 2
may accommodate one interface and no more than two
local I/O boards, therefore the maximum number of outputs, and inputs inside the enclosure is
limited to 2x16=32 outputs and 2x8=16 digital inputs. When this is not enough,
I/O
expansion unit
must be used. The
I/O expansion unit
will contain the
local I/O
interface
, the
I/O boards
, a
Motherboard,
and a
Power supply
, which may be AC or DC
depending on the availability of electric source. When the expansion is installed away from the
controller we call it a
Remote I/O unit
.
1
2
3
4
5
6
ON
1
2
4
8
16
32
The value represented
by each micro switch
