P
AGE
12
05774-0598 <90-00122>
OPERATION
that it is a slow to operate relay. (50 msec) After the slow to
operate period, TB will output a ground which will turn on relay
KB. This will remove the VF shunt and it will also turn on timer
TA which will place either a ground or battery on the E lead of
the PBX. The PBX will now be seized and the release of the
interface will be as described below.
R
ELEASE
OF
THE
I
NTERFACE
.
From the Order Wire
The user will dial the 3 digit code (1, 2, 3 for this example) plus
“#” and relay KA will turn on for 3 seconds when the 3 digits are
detected. When the “#” is dialed, the decoder will output a
ground on pin 27 through the operated KA contacts. Relay KC
will turn on and lock to the ground from the output of timer TB
which is being held by the E lead input on its input. (M lead
from the PBX)
Relay KC turning on will open the M lead from TA to the PBX E
lead. The PBX will have its E lead removed and relay KC will
not be able to release until the PBX removes its M lead to the E
lead of the VNET interface which will restore TB. When the
PBX removes its M lead (E lead on the VNET interface) TB will
release and the ground to KB and KC will be removed releasing
them.
KB releasing will replace its terminations on the VF bridge and
the PBX. KC releasing will reclose the TA output path to the
PBX E lead. TA is inactive and the PBX will not reseize. KA will
release after 3 seconds when the decoder resets itself. The ‘#”
detection is only on for as long as the tone is present. The
system is back to normal.
From the PBX side
The user of the PBX will hang up his phone and the PBX M lead
(E lead on the interface) will be restored. This will cause TB to
release and TB releasing will release TA and KB. The E lead
from the interface to the PBX M lead will be restored and the
PBX will be dropped.
KB releasing will replace the terminations on the VF bridge so
the order wire users will not hear any VF from the PBX.
