Table 2-32 On Delay Timer Function Block Example; Figure 2-40 Ondt Function Block Example - Honeywell UMC800 Reference Manual

2.43 ONDT Function Block,
Properties Group Parameter
Time Delay Time delay
Example
Figure 2-40 shows a Function Block Diagram using an ONDT function block.
PLC Ladder Logic
The application requirement is to turn on a pump, a compressor, etc. for
a fixed period of time - a common use for timers. This application, the
turn on of Pump2 for 300 sec., requires two additional rungs of ladder
logic. After SOL4 is turned ON, SOL 5 (Pump 2) is also turned ON
since CR1 (NC) is OFF (logic true). When ON Delay Timer 2 times out
after 300 sec., the CR1 coil is turned ON which turns off SOL 5.
UMC 800 Logic
In UMC logic, the output of ONDT4 timer activates the
ONDT1 timer directly and is also an input for a 2-IN AND
gate, whose output activates the DO for SOL5. After ONDT1
times for 300 sec., its output turns ON, disabling the AND
gate output which de-energizes the DO. Three (3) additional
function blocks are used.
3/99
continued

Table 2-32 On Delay Timer Function Block Example

Index#
0

Figure 2-40 ONDT Function Block Example

Function Block Reference Guide
Parameter Description
Delay Time - specifies the
amount of time the ON state
logic output will occur after an
OFF to ON transition of the
RUN input.
Function Blocks
Value or Selection
0.1 sec, 0 to 9999.9
Enter as 0.1 to 99999 in
0.1 increments
Start Stop
On Lamp
DO 1
DO 1
SOL 4
ON Timer
1
DO 2
DO 1
20 SEC
SOL 5
CR1
DO 3
DO 2
ON Timer
2
300 SEC
CR1
DO 2
115