RC Systems ST-72, Instruction Manual

Page: 112 / 142

ST-72 User's Manual
Document: UM-1007 Revision Level A
106
SECTION 7
WIRELESS OPTION
ST-72’s communication ports may be connected to a FHSS (Frequency Hopping Spread
Spectrum) wireless radio modem shown in
Figure7-1. There are two different frequency options offered, 900 MHz and 2.4 GHz.
900 MHz is available in a single port modem (10-0364) or dual port modem (10-0365).
2.4 GHz is also available in a single port (10-0357) or dual port modem (10-0358). The
dual port radio modems have two radio modules installed and can be used to receive
and transmit data simultaneously. The radio kit options allow three separate modes of
wireless operation. These are “Wireless Monitor” (
section 7.2 ) accepting data from ST-
48/RF sensor transmitters, “Wireless Modbus Slave” ( section 7.3 ) providing data to a
Modbus master ( master side of network requires additional radio), and “Wireless
Modbus Master” ( section 7.4 ) accepting wireless data from Modbus slaves ( slaves side
of network requires additional radio). When used in the “Wireless Receiver” mode the
radio must be connected to a port configured for
WIRELESS MONITOR . “Wireless
Modbus Master” mode requires the radio be connected to the ST-72’s RS-485 port
configured for
MODBUS MASTER
and “Wireless Modbus Slave” mode connects it to
the RS-485 port configured for MODBUS SLAVE ( Section 2.5.1.1 ). It is important to
remember RADIO SETUP functions described in section 7.1 may be performed from the
COMMUNICATION SETTINGS menu.
Each transceiver on a wireless network must have their
RADIO SETUP
menus
configured to share the same hopping channel (0-32) and System ID (0-255) to
communicate. All R.C. Systems wireless transceivers utilize a Server-Client network
where Clients synchronize their hopping to the Server. The Server transmits a beacon at
the beginning of every hop (50 times per second). Client transceivers listen for this
beacon and upon hearing it will indicate
InRange
with the LED on the radio modem
board and synchronize their hopping with the Server. Each network should consist of
only one Server. There should never be two servers on the same RF Channel number 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 (as opposed to a
battery powered ST-48/RF utilizing a “sleep” mode) and Servers typically should be
centrally located since all Clients must receive the beacon in order to communicate.