User`s guide

Appendix A - Logic Application Examples
On and Off Delay Timers
232 UMC800 Control Builder User’s Guide Release E
1/01
Example 2 - Using On delay timers for time duration
Start Stop
DO 1
DO 1
DO 1
ON Timer
1
20 SEC
DO 2
On Lamp
SOL 4
SOL 5
DO 3
ON Timer
2
300 SEC
DO 2
CR1
CR1
DO 2
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.
PLC Ladder Logic
UMC 800 Logic
PUMP 1
PUMP 2
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.
Example 3 - Using Off delay timers for time duration
An OFF delay timer block output is ON as long as the RST input is
logic HI (ON). It can be used for time duration but must be
triggered by an ON to OFF transition on the Reset input. This can
be accomplished using Trigger blocks to create one-shot pulses
which last one scan cycle. The fast logic trigger pulse will last 100
ms. while the normal logic trigger pulse will last the complete scan
cycle for analog blocks. Use according to application need. A
Periodic timer output pulse may also be used to start the timer for
the OFF delay.
Off delay
AND4 output
TRIG1 output
OFDT2 output
Timing Diagram