Hartcran House, 231 Kenton Lane, Harrow, Middlesex, HA3 8RP, England
Tel: +44 (0) 20 8909 9595, Fax: +44 (0) 20 8909 2233, www.radiometrix.com
Issue 2, 30 July 2012
PLT / PLR
NBFM Multi channel Data Packet Link Radios
Inexperienced users of ISM band radio modules often
require a totally transparent interface. This can require
considerable processing power, and buffer memory,
to be provided in the radio device.
The more experienced user, on the other hand, may
not want to write a raw radio interface, but desires a
module that gives more control over the datastream
than a 'beginners' solution.
The PL radios represent such a compromise solution.
Features
Figure 1: PLT2 transmitter and PLR2 receiver
Conforms to EN 300 220-3 and EN 301 489-3
High performance double superhet. PLL synthesizer with TCXO
SAW front-end filter
User interface speed: 9600bps for standard module
Usable range over 1km
Fully screened. Low profile
Re-programmable via RS232 interface
Low power requirements
Applications
Wireless handheld terminals
EPOS equipment, barcode scanners
Data loggers
Industrial telemetry and telecommand
In-building environmental monitoring and control
High-end security and fire alarms
DGPS systems
Vehicle data up/download
Heavy vehicle/machinery controls
Technical Summary
Operating frequency: 173.200 - 173.325MHz (UK band)
o
150.825 - 152.450MHz (Australian Band)
o
433.875 - 434.650MHz (EU band)
o
458.525 - 459.1MHz (UK band)
Other custom VHF and UHF bands
32 channels @ 25kHz channel spacing
Transmit power: +10dBm (10mW) / +20dBm (100mW)
Supply range: 3.1 – 15V (TX @ 10mW and RX), 4.1 – 15V (TX @ 100mW)
Current consumption: 34mA @ 10mW, 90mA @ 100mW (transmit) and 20mA (receive)
Data bit rate: 5kbps max. (standard module)
Receiver sensitivity: -118dBm (for 12 dB SINAD)
Serial configuration by inverted RS232 at 3V CMOS level
Evaluation platforms:
NBEK + PL carrier
Radiometrix Ltd
PLT/PLR Data Sheet
page 1
PLT / PLR data packet link radios
The PL modules use the hardware of the existing LMT/LMR transmitter receiver pair, combined with
completely new firmware to produce a simple to use but readily controllable data link
Both radios have a similar pinout. The bidirectional DATA pin requires an inverted RS232 data interface, at
3V CMOS logic levels (Both DATA and FLOW are bidirectional. As outputs they are open drain pins with 50K
pullups to the internal Vcc, and 470 series protection resistors. Do not exceed 3v on these pins).
The CMD pin selects the operating mode: If pulled low, then serial data is routed to a command interpreter
(see 'programming') . If high (floating) then received bytes are loaded into the buffer (the PLR receiver only
inputs data in command mode of course).
When the buffer is full, the transmitter either sends a databurst immediately, or waits for a command from the
user
The transmitter data buffer size is pre-set by a user command (from 1-32 bytes)
The data format uses is modified biphase at a peak data rate of 2500 bits per second.
Each burst consists of a framing sequence, a two byte address, a two byte checksum, and a variable length
(1-32 bytes) data 'payload'. The payload length information is coded into the framer sequence.
Minimum length (1 byte) bursts take about 70mS (including all transmitter setup and power on/off timings),
while a full 32 byte burst requires over 250mS.
Data transfer rate is limited by the interface's inability to receive data while transmitting a burst (if FLOW is
high, then the PLT is not listening to the serial port at all), or to decode received packets while in the process
of outputting one
The standard products use a 9600 baud user interface speed. Slower versions are also available (1200,
2400 and 4800 baud, with suffixes -1, -2, and -4). The baud rate is not user programmable.
Radiometrix Ltd
PLT/PLR Data Sheet
page 2
Radiometrix Ltd
PLT/PLR Data Sheet
Figure 2: PLT block diagram
page 3
Figure 3: PLT footprint (top view)
Pin description –
PLT
Pin
1a
2a
3a
4a
1b
2b
3b
4b
Name
Vcc
0V
TXE
TXD
CMD
DATA
FLOW
T
out
Function
3.1 – 15V power supply (@ 10mW)
4.1 – 15V power supply (@ 100mW)
Ground
Transmit Enable (active low)
(link to 4b)
Command mode select input
Serial data out/in
Buffer full / busy output
(link to 4a)
Notes:
1. This pinout is very similar to the LMT radios but the serial data is on pin 2b (not 1b, which is here
used as the command mode select input )
2. Serial programming is by an inverted, CMOS logic level, 9600 baud RS232 datastream applied to
the DATA pin (2b).
3. TXE has a 100kΩ pullup to Vcc
4. All pins are on an 0.1" grid
5. In the 'off' state a PIN switch open circuits the RF output pin. There are no 'off' state spuri.
6. 10mW unit will operate (with marginally reduced specifications and lower (6-8mW) output power)
from a 3.0V rail. This must be well regulated and without noise or ripple, as in this state the unit's
internal regulator no longer operates, and provides no supply rejection.
7. 100mW versions should not be run continuously from supply voltages > 9v
8. Do not exceed 3v logic levels on any input (4v for 100mW PLT units)
Application circuit
Antenna
3.1- 15V
T
ransmit enable (active low)
VCC (1a)
GND (2a)
T (3a)
XE
T (4a)
XD
PC serial port
6
7
T
XD
2
3
4
Vc c
(0-3V)
PLT
2
SGD
Figure 4 : Typical RS232 interface for programming and data input
Radiometrix Ltd
1
5
8
9
PLT/PLR Data Sheet
page 4
Radiometrix Ltd
PLT/PLR Data Sheet
Figure 5: PLR block diagram
page 5
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