QTech Data Systems Wireless Point to Point (WP2P) - Digital I__O - Manual (Page 5)

Wireless Point to Point - DIGITAL – Quick Start Guide – v2.1 – June 2013 5
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WP2P systems to be used in the same location. The “Channel number” is identified by the “#”
on the packaging label; this example is “Channel #1”.
Warning – Do not use the same channel for adjacent systems.
For example, if you currently use “#1” ensure the adjacent system is “#3” etc.
Operational note – How do the modules communicate?
The WP2P modules use an “event driven” approach to communications. When the state of
any input changes the WP2P module will immediately communicate that change to the other
WP2P module. This approach results in very fast response times.
If the communications link between a pair of WP2P modules goes down (for example if one of
them loses power), then the relay output state of the on module is maintained at the value it
was prior to the link going down.
When the WP2P modules detect a change of their input state, they will immediately transmit a
message to the other module. There is a very small chance that another WP2P module on
that channel also wanted to send a message at exactly the same time. This will result in a
“collision”, but the WP2P modules can detect that a collision has occurred, and will then use a
collision avoidance scheme to retransmit their messages.
Specifications may be subject to change