Receive Timeout (Secs); Time Message Deviation (Secs); Consolidated Time Server (Checkbox); Max Time Change Within Minutes (Min) - Siemens VIU-20 Installation And Instruction

VIU WEB BROWSER USER INTERFACE
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External via Class C/D Messages
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When this option is selected, the internal GPS receiver in the VIU is ignored and current time and
date information is provided by the Interoperable Train Control messages being received via
Ethernet.
SNTP Client
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When this option is selected, the internal GPS receiver in the VIU is ignored and current time and
date information is provided via SNTP.
7.3.7.2

Receive Timeout (secs)

If the VIU does not receive a valid NMEA data stream or time message within the "Receive
Timeout" number of seconds, it will declare the GPS status bad. For the internal GPS receiver,
this will only occur if the internal receiver or circuit board malfunctions. For an external GPS
receiver this will occur if the GPS-to-VIU cable is unplugged.
Receive Timeout range: 0 (off) – 86400 seconds (24 hours) in increments of 1 second (default =
5 seconds).
7.3.7.3

Time Message Deviation (secs)

If the Time/date received in the GPS NMEA data stream differs from the internal VIU clock by an
amount equal to or greater than the Time Difference setting in seconds, the VIU will set its
internal clock to the time/date in the GPS data. Otherwise, the VIU will not adjust its clock.
Time Difference range: 0 – 3 seconds (default = 1 second).
7.3.7.4

Consolidated Time Server (checkbox)

When this box is checked, the VIU becomes a Consolidated Time Server. If the VIU has a GPS
time source – either its internal GPS receiver, an external GPS receiver, or a time source via
Class C/D Ethernet -- the VIU will issue time and date information via Ethernet to all other VIUs
once every hour. This allows VIUs which are co-located at a site to require only one Internal GPS
Receiver or one externally mounted GPS antenna, provided the co-located VIUs are connected
via the same Ethernet subnet.
One VIU may be configured to be Consolidated Time Server to all other VIUs, provided the other
VIUs do not already have an active GPS source for time and date. If a VIU is configured to be a
Consolidated Time Source and has an active GPS receiver (either internal, external, or via
Ethernet) the VIU will ignore time and date messages sent by any other VIUs that are configured
as Consolidated Time Sources.
7.3.7.5

Max Time Change Within Minutes (min)

This is the number of minutes that the VIU keeps Time Update records for. If it is set to 60
minutes, the VIU keeps track of all Time Updates for the past 60 minutes. If the total
accumulated drift of time within those 60 minutes exceeds a configurable number of seconds, the
VIU disallows the sending of Wayside Status Messages to the Application Gateway and the VIU
starts a time resynchronization process. Time Update records that are older than 60 minutes get
discarded so that at any one moment in time, the VIU has a record of only the latest 60 minutes
of Time Update information in its RAM.
Time Difference range: 1 – 120 minutes (default = 60 minutes).
SIG-00-07-11
Version No.: B.2
7-20
SEPTEMBER 2012 (REVISED OCTOBER 2019)