BASIC APPLICATION GUIDELINES & PROGRAMMING
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5-35
SIG-00-22-02 JUNE 2022 (Revised September 2022)
Version: B.1
If the receiving unit does not get a valid message from its neighbor in the time specified by the
Msg Timeout
then the receiver will revert the received bits on this link to the de-energized
state.
For example, when the
Msg Timeout
field is set to the default setting of 3600ms and a new
message is not received within 3.6 seconds of the last message, the GCP5000 (GCE):
•
designates the link as failed
•
defaults to a restrictive set of states for the message data on the failed link
•
de-energizes the Vital Comms Outputs
The default setting for the
Message Update
parameter is 800ms. At this default value,
approximately 4 messages can be lost on the radio link without the link failing.
5.5.3 Version
The Version field is used to check the consistency of the interface; if the version is inconsistent
on either side of the Vital Comms link, the Vital Comms link will remain out of session. For
example, consider the case of a system that is already installed in the field with two GCE
systems communicating via Vital Comms Link 1 and using a Version of 1. If a change is made
to the interface, for example changing what the message bits are used for, it is recommended to
update the version. This will then avoid any compatibility issues where one side of the link has
been updated but the other side hasn’t been updated.
5.5.4 Assigning Transmit and Receive Bits
When the Vital Comms Link has been enabled, two more menus are enabled which allow the
user to assign the bits received on the link as shown in Figure 5-26 and set the state of the
transmitted bits as shown in Figure 5-27.
The Vital Comms Link Rx menu allows the user to directly assign the state of the received bit to
a
System Input
. For example, if the approach circuit consists of multiple PSO track circuits and
one of these is remotely located. Then its state could be sent via a comms link to the GCE at
the crossing and used to set the PSO 1 RX 1 Enable as shown in Figure 5-26.