QTech Data Systems Wireless Point to Point (WP2P) - Digital & Analogue I__O - Manual (Page 6)

Wireless Point to Point - DIGITAL & ANALOGUE - Quick Start Guide – v1.1 – June 2013 6
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Internal Fuse
The WP2P module circuit is protected by a 20mm x 5mm 500mA fast blow fuse. This is
located on the internal circuit board. To access the fuse, remove the top cover by prizing it off
its retaining dimples. Only replace the fuse with an identical type, do not use alternatives.
Radio Address (RA)
All WP2P systems have a unique “radio address” which is programmed into WP2P modules
during manufacture.
The radio code is represented and specified in the following format “192.168.0.0”, it is a
security measure to prevent unauthorised users.
Note – All WP2P modules in a given system must have the same first three
numbers in their “radio address” and the 4
th
number must be a sequential pair starting
from the even number e.g 0.1.1.40 & 0.1.1.41. The code is on the rear of WP2P
modules. The radio code must be stated for purchasing for WP2P module replacement.
Using Multiple WP2P Systems in the same area
There are ten individual frequency bands referred to as “Channel numbers” allowing up to ten
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 notes – 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.
In addition to the switch input state change message and the keep-alive message, the WP2P
– DIGITAL & ANALOGUE modules will send a message when their analogue input value has
changed by greater than 2.5%FSD since the last time it sent any message. (2.5%FSD is
0.5mA for a current loop configured module). This means that for a very fast changing
analogue input value, the corresponding output will be always within 2.5% of the input value.
Then, when the module sends a keep-alive message or a switch change message, the
current analogue input value is also sent, so the output value will be equal to the input value.
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