2
STANDARD OPERATION
The 781N provides a choice of two methods of electric latch pullback: Single System or Dual
System
SINGLE SYSTEM LATCH PULLBACK
This method allows one input to control two devices sequentially. A momentary switch closure
across terminals 1 and 2 of TB3 will pull back DEVICE ONE first, followed by DEVICE TWO. Use
this method for single door applications or on a pair of doors using a device on one or both leaves.
The 781N comes from the factory already set up for this method.
DUAL SYSTEM LATCH PULLBACK (OPTIONAL)
This method allows independent control of DEVICE ONE and DEVICE TWO outputs by their own
separate input. A momentary switch closure across terminals 1 and 2 of TB3 will pull back DEVICE
ONE only. A momentary switch closure across terminals 7 and 8 of TB3 will pull back DEVICE
TWO. No more than one device can be used per output. Use this option for applications requiring
two single door systems or two pair door systems using one device on the active leaf of each pair of
doors. To change over to the optional dual system latch pullback, move the program jumper PJ1
from between the middle post and the end post, marked "S" (Single System) to between the middle
post and the end post, marked "D" (Dual System).
NOTE:
When using the optional method, DEVICE ONE and DEVICE TWO can never be activated
at the same time in the event that both input switches are actuated simultaneously. If this
should occur, DEVICE ONE will always activate first, followed by DEVICE TWO.
When using a momentary, normally open switch for activating latch pullback, adjust pot R2 (for
DEVICE ONE) or pot R4 (for DEVICE TWO) on the p.c. board to the desired latch pullback delay
time from 1 to 20 seconds. Turn the pot clockwise to increase the delay time.
When using normally open contacts from a keypad or card reader ( with built-in time delay) or a
maintain switch, turn pot R2 (or R4) fully counterclockwise to the minimum delay time (approx. 0.5
sec.). A contact closure will activate latch pullback. Upon opening of the timed or maintained
contacts, the device will latch within 0.5 second.
Each modified exit device contains a pulse module which delivers a pulse at approx. 24VDC to a
high current coil inside the exit device every 6 seconds until the latch is finally pulled back all the
way. At this point, a control rod passes over a reflective sensor and signals the module to stop
pulsing. There is always an initial pulse that occurs at the moment the system is activated. During
the period the system remains activated, output voltage is applied to a low current secondary coil.
This coil is responsible for holding the latch in the "pulled back" position until instructed to return to
the "fail secure" position. (See note 2 on page 5.)
An ASSA ABLOY Group brand
80-9477-0781-010 (01-13)
