Rockwell Automation 1747-DSN DISTRIBUTED I/O SCANNER - Manual (Page 30)

Chapter 3
Configuration and Programming
3–12
Programming Example Using 7 I/O block Configuration
In the following programming example, the first rung is used to initiate the
DIO system using the Output Control Word. The scanner is located in slot 1
and an alarm is connected to a discrete I/O card in slot 2. When the water
level drops, the switch closes and the pump starts pumping water into the
tower.
The Communications Status Bit for I/O block 1 is used to ensure that input
data from the I/O block is valid before the pump can be turned on (rung 5).
It is also used to turn on the alarm if communication with the I/O block is
lost for more than 6 seconds (rungs 3 and 4).
MVM
MOVE
Source
N7:01
Mask 1F
Dest O:1.00
(U)
0
O:2.0
] [
S:1
15
] [
S:1
15
(L)
10
O:1.0
(U)
9
O:1.0
TON
TIMER ON DELAY
Timer
T4:0
Time Base 0.01
Preset 600
Accum 0
I:1.0
1
(EN)
(DN)
(L)
0
O:2.0
] [
T4:0
DN
I:1.1
0
( )
0
O:1.1 I:1.0
1
END
Integer file N7:01 sets the bits for Number of I/O Blocks (rung 1). By setting these bits
in this manner, you can change the number of I/O blocks for which the scanner is
configured by entering the program mode, changing N7:01 and re–entering the run
mode.
Configuration
Data Valid bit
Disable Outputs
bit
Turns alarm off
Communications
timed out timer
Turns alarm on
Pump motor
First scan bit
First scan bit
Communication
Status bit for I/O
block 1
Communications
timed out bit
Float switch input
Communication Status
bit for I/O block 1
Rung 2
Rung 1
Rung 3
Rung 4
Rung 5