Owner's Manual
GDX-350 Sensor Transmitter
P/N: 5600-9001 Rev 2 7
Figure 1-2: Data Displays (RF Version) SHOWING Radio Status
1.3. The RF Transmitter and Client/Server Wireless Networks
Wireless transceivers utilize a FHSS (Frequency Hopping Spread Spectrum) Server-Client network where
multiple
clients synchronize their frequency hopping to a single server
Each GDX-350 wireless “broadcast” includes 10-bit monitored gas value, battery voltage and a status
byte. This proprietary wireless protocol interfaces only to GDA-400 and GDA-1600 controllers.
Controllers are capable of functioning as Clients
. The Server transmits a beacon at
the beginning of every frequency hop (50 times per second). Client transceivers listen for this beacon and
upon receiving it synchronize their hopping with the Server. Since RF GDX-350s are powered by a small
battery, much care is taken to reduce power consuming RF transmissions to a minimum. For this reason
RF-configured GDX-350s are unsuitable for Server operation and are always Clients.
or
Each transceiver on a wireless network must have its RADIO SETUP menus configured to share the
same Hop Channel (0-32) and System ID (0-255) in order to communicate. There should never be two
servers with the same Hop Channel / System ID settings in the same coverage area as the interference
between the two servers will severely hinder RF communications. The Server must be in a powered
location and should be centrally located since all Clients must receive the server’s beacon in order to
communicate.
Servers, but only one Server is allowed per wireless
network. Multiple controllers may receive the same transmissions from RF-configured GDX-350s, but only
one controller per wireless network may be configured as the Server.
Correct planning and design of wireless systems are imperative for ensuring a successful installation. It is
highly recommended that a site drawing indicating location of monitors and base station, line of site
obstructions, and sources of RF interference be submitted when requesting a quotation.
1.3.1 Radio Status Icons ( )
Figure 2-1 shows the data displays and identifies “radio status” (RS) icons which appear on the LCD of
RF-configured GDX-350s. RS icons, along with the TXD led (see Figure 1-2), are useful diagnostic tools
for evaluating RF communication. Status conditions indicated by the RS icon are Sleep Mode - Zzz’s,
Server In Range -
(server’s beacon received at most recent attempt), Server Out of Range -
(server’s beacon not received at most recent attempt), Server Previously Out of Range -
and Low
Battery -
. The Server “Previously Out of Range” icon is useful in determining if intermittent
communication failures are a result of this monitor having problems receiving the Server’s beacon. The
duration and frequency of “out of range” conditions are stored in the Event Log table. Low Battery
conditions also flash the FAIL LED.
It is important to understand RS icons only update as the TXD LED flashes indicating an RF transmission
has occurred. The adjustable (see Wakeup Time menu) RF transmission rates are typically each 5-
minutes, but increase to each 6-seconds during alarm conditions.