B-1
APPENDIX B. ALTERNATE BASE STATION CONFIGURATIONS
The basic base station consists of a computer and the RF232T Base Station. There are other options
for a base station including a portable base station, a phone-to-RF base station, and a phone-to-RF
base station with measurement capability.
B.1 THE PORTABLE BASE STATION
The portable base station is an aid in setting up
a large radiotelemetry network, or in trouble-
shooting RF network communication problems.
A portable base station allows any of the field or
repeater stations to act as a base station.
Therefore, to try any particular RF link, it is not
necessary to travel to the fixed base station.
The fixed base station computer should not be
used when using a portable base station. This
will simplify testing. If an OS/2 laptop is not
available, a DOS laptop, loaded with
GraphTerm, can be used to test RFLinks (see
Section 4.2).
Figure B-1 is a block diagram of a portable base
station. The SC532 is the interface from the
laptop computer to the RF95T Modem. The
transformer on the SC532 should be cut 6" up
the cable. The two leads on the SC532 should
be stripped and tinned for connection to a
battery. Most laptops have a 9-pin RS232 port,
so a 9- to 25-pin RS232 cable is needed to
connect the computer to the SC532.
B.2 PHONE-TO-RF BASE STATION
When an RF network is a great distance from
the desired place of data collection, a phone
modem can be used to call the RF base station.
A computer and a Hayes phone modem can
call a phone-to-RF base station. The
configuration is shown in Figure B-2.
The Station File at the computer must include
the following interface devices: COM Port,
Hayes Modem, and then RF Path. The
PS512M Power Supply and Charging Regulator
supplies 5 V to the RF95T and DC112, supplies
12 V to the RF100 or RF200 Radio, and acts as
a null modem between the DC112 and the
RF95T. The RF95T and DC112 are both con-
nected to a separate 9-pin port on the PS512M.
The RF95T Station ID at the phone-to-RF base
station must be 255 to allow more than one
field station to be called without terminating the
initial phone link. The RF95T in the RF95T-ME
State recognizes Station ID 255 as a command
to answer the phone and hold the ring line high
which keeps the Modem Enable line high after
the Ring from the Hayes has quit.
FIGURE B-1. Portable Base Station
