Honeywell HC900 - Figure 62 OFDT Function Block Example

Function Blocks
OFDT Off Delay Timer Function Block
230 HC900 Hybrid Control Designer Function Block Reference Guide Revision 11
2/07
Example
HFigure 62 shows a Function Block Diagram using an OFDT function block.
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
Figure 62 OFDT function block example