Lenel Onguard false door forced open alarms problem

[Scott Crumpton]

I'm seeking the opinion of a someone having experience with the Lenel
Onguard system to help me in resolving a problem with false forced
open alarms on a new install.

Here's the situation: We just installed 6 doors using LNL-1320
controllers, electrified strikes, and PIR for REX. The problem is that
we're getting numerous false forced open alarms on exit. We've had the
installers working to resolve the problem. It's gotten better, but
it's not fixed.

Initially, the PIRs were set with a 6 second hold time. The scenario
is two people standing under the PIR (REX is active), one opens the
door and leaves (REX is still active), the door closes (REX is still
active), the other opens the door to leave (REX is still active) and
gets a forced open alarm. If the REX is allowed to cycle the alarm
does not occur. Clearly the LNL-1320 requires one REX transition per
door opening.

The installer's solution was to shorten the PIR hold time to the
minimum of .25 seconds. That fixed the original problem. The new
problem is that if a person pauses for just an instant before opening
the door a false forced open results because the REX goes inactive.

The solution to that was to increase the PIR hold time back to 6
seconds and change the door status contact to a dual switch. The
second circuit being used to interrupt the REX when the door is
opened. This has the effect of cycling the REX when the door is
opened, thus satisfying the one door event per REX requirement of the
LNL-1320.

It works most of the time. But every once and a while a false forced
open will occur for no apparent reason. It's my opinion that having
the two switches (door status and REX interrupt) co-located results in
a timing problem for the 1320. Most of the time it gets it right, but
sometimes it sees the REX drop before the door status opens. I believe
the correct wiring solution is to place a separate REX interrupt
switch at the top of the door about 10" out from the hinge. This will
insure that the REX is interrupted after the door status switch
(located at the strike) registers door open.

A firmware solution (to allow multiple door opens per REX) is also
possible, but somehow I don't think that will happen.

So, does anyone have any opinions on this? And how should the LNL-1320
be used with a PIR REX device?

Thanks in advance,
---Scott.

 

[Scott C]

This doesn't seem to have made it the first time. Sorry if you see it
twice.

Sounds like your
shunt time is too short, and your not programmed to reset the REX time in
conjunction with the Door Position Switch (Door Contact). Once the door goes
to normal (Door closed) the timer should reset for the next REX.

The REX time is being controlled by the PIR device and I don't think
it has a reset or cancel input. That would solve the problem nicely.
I'll have to check the specs on the PIR. The idea of having another
door position switch was to interrupt the REX signal, since the 1320
appears to require a unique REX for each door opening.

If you have
a lot of traffic next to this door, you may consider placing a manual push
button for the REX process.

I would be drawn and quartered if I suggested that!

Lenel said that the reason for the one REX per door opening was to
detect a failed REX device. If multiple door openings per REX are
allowed, then a REX failing in the on state would never be detected.
Ok, but which would you rather have - The potential for a failed REX
going unnoticed or a constant stream of false alarms. What's an
acceptable false forced open rate for a door? I haven't run the
numbers, but I guess that most of our doors with mechanical REX are
running around 1 in 500 for exit and near zero for entry. These new
PIR REX doors are running at about 1 in 20 on exit. The monitoring
staff is going crazy and there's no way we can treat any of these
alarms seriously.

I feel a bit like I've hit a wall. I would like to demand that the
installer put a separate switch up at the top of the door about 10"
out from the hinge to interrupt the REX _after_ the door position
switch at the strike opens. But I feel if I do and it doesn't solve
the problem, then I'll loose all credibility. I'd like to know how
someone else has wired the LNL-1320 to work with a PIR REX before I
take this step.

Thanks for your input Jack, and I'll check the PIR for a reset.

---Scott.