Campbell Scientific RF300-Series DRL VHF/UHF Radio Transceivers - Manual (Page 19)

3-1
SECTION 3. RADIOTELEMETRY NETWORK COMPONENTS
3.1 RF95A MODEM
The RF95A is an interface between the
computer and the radio when used at a base
station, and an interface between the radio and
the datalogger at a field station. In a repeater
station, the RF95A is an interface between two
other communication stations.
The RF95A replaces Campbell Scientific's
RF95, DC95 and SDC RF Modems. The
RF95A is compatible with previous modems.
Refer to Appendix F “Equipment Compatibility"
for compatibility considerations. The RF95A is
the same RF modem as the RF95, except the
RF95A strobes power to the RF300 radio and
uses a different operating system. This is done
to reduce current consumption and extend
battery life. The RF95A should be used with the
RF300 radio.
3.1.1 PHYSICAL DESCRIPTION
The front panel of the RF95A is shown in Figure
3-1. There are two ports for interfacing external
devices. The port labeled TRANSCEIVER
connects to the radio, and the port labeled
SERIAL I/O connects to the datalogger,
PS512M or CH512R in the case of a repeater or
phone-to-RF base station. The red light labeled
CARRIER DETECT is used primarily to indicate
when a carrier frequency has been detected by
the radio. The RF95 to RF100/RF200 cable is
different than the RF95A to RF300 cable.
3.1.2 RF95A STATES
The RF95A Modem operates in one of two
separate states. The RF95A can be utilized in
either the RF95A-ME (Modem Enable) state or
the RF95A-SDC (Synchronous Device
Communication) state. The proper state must
be determined before employing the RF95A in
the field. A switch inside the RF95A needs to
be set accordingly.
The RF95A-ME state is ALWAYS used with
21X and CR7 dataloggers. The RF95A-ME
state is NORMALLY used with all dataloggers.
SDC compatible dataloggers (CR10, CR10X,
CR23X, CR510, and CR500) can also use the
RF95A-SDC state. The SDC state has the
advantage that a phone-to-RF base station can
have measurement capability. Only the RF95A
at a phone-to-RF base station with
measurement should to be switched to the
RF95A-SDC state.
A switch with nine different dip switches is
inside the RF95A; the RF95A cover must be
removed to locate the switch. The ninth switch
sets the RF95A state. The RF95A-ME state is
chosen by setting the ninth dip switch open,
represented by 1. The RF95A-SDC state is
chosen by setting the ninth dip switch closed,
represented by 0. Refer to Figure 3-2.
RF95A
FIGURE 3-1. The RF95A Modem