
INTRODUCTION
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1-2
SIG-00-07-11 SEPTEMBER 2012 (REVISED OCTOBER 2019)
Version No.: B.2
WARNING
PLEASE REVIEW THIS USER MANUAL CAREFULLY TO
ENSURE CORRECT APPLICATION AND MAINTENANCE OF THE
VITAL INTERFACE UNIT (VIU). INCORRECT APPLICATION MAY
RESULT IN UNSAFE OPERATION
.
1.2.1 Wayside Interface Application
In the Wayside Interface application (Figure 1-1), the VIU can monitor switch positions and
signal aspects controlled by other equipment in an interlocking and send the signal aspect and
switch position information to an on-board system. This application is for use in PTC systems.
See Section 5 for details.
NOTE
When used in a PTC application, the VIU would function as the
Wayside Interface Unit or WIU.
Figure 1-1 VIU Used in Wayside Interface Application
Switch
Input
Switch
Input
Lamp
Input
VIU
(WIU)
VIU
(WIU)
VIU
(WIU)
LAN
LAN
VIU
(WIU)
11-11_ITC_WSDE_INTRFC
08-05-11
Ethernet
Switch
Input
Lamp
Input
ITCM = Interoperable Train Control Messaging System
ITCM