VSS-401-x Installation and Operation Manual
Document # 540335, Rev IR, 10/2006
Page 13 of 21
3.8
Built-In-Test (BIT) Capabilities
External status LEDs aid in determination of state of ±5V power supplies,
sequence select input, briefer activation input, and currently selected
input. These LEDs provide simple diagnostics to test for shorted inputs to
the VSS-401
.
When powering up, if any of the input select pushbuttons or sequence
button inputs are active, this is considered a fault condition. The status
LEDs will blink on and off until the fault condition is cleared. The status
LED associated with the input with the fault condition, will not blink, but will
remain in the ON state. When the fault condition is cleared, only the status
LED associated with the active input will remain lit.
3.9 Discrete
Interfaces
Active and inactive states for each input are defined below as follows:
PIN NUMBER
ACTIVE STATE
INACTIVE STATE
P1-3 through
P1-7
Momentary Ground
(< +3.0VDC for >50msec)
Open (pulled up to apx +28V)
P1-8
Mom or Const GND (<+3VDC )
Open (pulled up to apx +28V)
P1-9
Constant Ground (<+3VDC )
Open (pulled up to apx +28V)
Active and inactive states for each output are defined below as follows:
PIN NUMBER
ACTIVE STATE
INACTIVE STATE
P1-4 through P1-7 Constant Ground (< +0.1VDC)
Open (pulled up to apx +28V)
Pins P1-4 through P1-7 serve as both active inputs and outputs.
3.10 Return To Last State / Power Up Default
Upon power-up, processor determines state of pin P1-8. If grounded, unit
sets the input channel selection to the last state prior to previous power-
down. If pin P1-8 is not grounded, unit selects Input #0 as the power-up
default.
During operation, if pin P1-8 is set to ground, unit shall select the previous
input channel (last state).
3.11 Video
Interfaces
All video interfaces are consistent with standard composite analog video
signals, 1 V
(p-p)
nominal. Unit is capable of handling various analog video
standards (NTSC, PAL, SECAM, etc.)
