DECODE PRM4 User manual

DECODE
Radio modem PRM4 868MHz
User's manual v1.6
http://www.decode.rs

Table of Contents
1 Introduction...............................................................................................................4
2 Modes of operation....................................................................................................5
3 Installing the device...................................................................................................8
3.1 Power supply..................................................................................................8
3.2 Serial connector..............................................................................................8
3.3 The antenna connector.................................................................................10
3.4 Signaling lights............................................................................................10
3.5 Jumpers........................................................................................................11
4 AT command set......................................................................................................12
4.1 Setup of the serial interface parameters.......................................................14
4.2 Setup of the ra io interface..........................................................................15
4.3 Comman mo e setup..................................................................................16
4.4 Re uce power consumption mo e setup....................................................16
5 Firm are update.....................................................................................................18
5.1 The proce ure for writing the new firmware...............................................18
6 Technical specifications..........................................................................................19
Ra io mo em PRM4 868MHz /User's manual V1.6 / 24.05.2011 2

Document history
Date 29.04.2009 Initial version of the ocumentv1.0
Date 23.06.2009 Revision v1.1
Date 09.12.2009 Revision v1.4 A e AT comman s EC an ET. Correcte the
AM comman format.
Date 08.02.2010 Revision v1.5 Bug relate to incomplete flushing of transmit
buffer when sen ing ata by full-buffer criteria, correcte .
Correcte bug relate to saving of parameters which haven't
been save with ATWR comman while exiting comman
mo e. New function intro uce to keep the same bps an ata
format while entering comman mo e with +++ sequence.
New function that set spee to 9600 bps an ata format to 8N1
while entering comman mo e with SET pushbutton. Bug
relate to same spee 9600 bps while entering comman mo e
with SET pushbutton, correcte .
Date 24.05.2011 New parameter ReceiverThreshol a e for setting of receive
level in Sleep mo e an averaging RSSI values for arbitration
of receiver wakeup.

1 Introduction
Deco e PRM4 mo em is use for ata transmission in UHF ISM 868MHz ban .
Through the use of ra io interface it procures networking of evices an systems.
Easy to use, the PRM 4 provi es secure metho of connecting computers, PLC
evices, measuring evices an SCADA systems.
The evice transports the asynchronous serial ata between two or more PRM4
evices in point-to-point or point-to-multipoint configuration. The RS-232/485/422
connection enables the implementation of the evice into the existing systems without
the nee for a itional equipment.
PRM4 Device
The stan ar elivery contains the PRM4 evice, network power supply a apter for
230V, mini omni- irectional antenna for ISM 868MHz ban , DB9 M-F serial cable
an CD with this manual an necessary software.
Ra io mo em PRM4 868MHz /User's manual V1.6 / 24.05.2011 4

2 odes of operation
Deco e PRM4 evice can operate in one of the two mo es of operation.
When powere , the evice will automatically enter the efault, data transfer mo e.
When the evice is in the data transfer mo e, it will listen an receive all the packets
inten e for it, whereas the transmitter will turn-on only occasionally to sen the ata
acquire from the wire connection.
The mo e an parameters of operation are set through the use of AT comman s using
the command mo e of operation. The transfer into the command mo e an the set of
supporte AT comman s is escribe in chapter 4.
The PRM 4 evice supports an a ressing scheme. All mo ems inten e for ata
exchange in a ra io network must be set to the same frequency an must have the
same network address (NA). The NA can be set to any value from the 0 – 65535
range. Each evice has its source address (SA) use to i entify the evice insi e a
network. The SA can take values between 0 an 255 inclusive. Note that the SA must
be set uniquely insi e a network. If a point-to-multipoint connection is require (e.g.
for master-slave protocols use with SCADA software or PLC evices) the
destination address (DA) masking is use . This way it is possible to mask a number
of bits when comparing the DA an SA an , consequently, the packet with one
estination a ress can be sent to multiple evices having the unmaske parts of their
SA match the unmaske parts of DA.
For example, if assume that the ra io frequency an the NA are the same for all the
evices in the following figure, the evice with the SA equal to 100 will sen its
packets to the remaining three evices, whereas the evices with the SA 1,2 an 3 will
sen ata only to the SA 100 evice. This is because the Address Masks (AM) on
evices with SA 1,2 an 3 have been set to 252 (binary 11111100) so that they match
the higher (unmaske ) six bits of the DA (binary 000000).
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Point-to-multipoint connection
The below figure illustrates the point-to-point connection. The AM is set to 255 so all
the bits are compare an only the exact match of the SA an DA woul lea to
receipt of the packets. The NAs as well as the ra io frequencies are set as with the
previous example.
Point-to-point connection
The PRM 4 evice receives over the serial interface an buffers the ata that nee s to
be sent until the con ition for sen ing the ata is met. The ata is sent when there are
no new ata for a specifie time interval after the last ata has been receive on the
serial interface. This time interval can be set by using the AT comman s an it is
referre to as the packetization timeout. The efault value of this parameter is set to
5ms. In other wor s, if communicating on 9600bps, a 5 character pause will in uce
the mo em to sen the entire memory content within one packet. The transmit ata
buffer size is 512 bytes.
The following figure shows the example of three-character packet generation an
sen ing on 9600bps with efault packetization timeout.
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Packet generation and sending
In cases when there is a nee for low power consumption of the evice (i.e. solar or
battery power) the evice can be set into one of the three re uce power consumption
mo es by using the ATSM comman . When in the re uce power consumption
mo e, the receiver is not constantly turne on. It is turne on an off 8 times per
secon . Therefore, when using this mo e, waiting for all the receivers to become
active may in uce the a itional transport elay. By using the ATSM comman the
re uce power consumption mo e of operation can be a juste to fit the various fiel
configurations. If the evices with the re uce power consumption are
communicating only with a evice in a normal mo e, the first group of evices is set
to ATSM2 whereas the evice operating in normal mo e is set with ATSM1. On the
other han , if all the evices are operating in low power consumption mo e, they
ought to be set with ATSM3.
Important note: When calculating the power bu get for the re uce power consumption mo e, the
RS232 signal lines shoul not be omitte . It is recommen e that, in these cases, the transmit/receive
signals of the RS232 interface shoul be switche off when not actively communicating.
Ra io mo em PRM4 868MHz /User's manual V1.6 / 24.05.2011 7

3 Installing the device
3.1 Power supply
The PRM 4 is powere by 5 to 28 VDC or 3.3 to 12VDC in battery powere version
of the pro uct. The stan ar current rain is less than 50mA with the transmitter
turne on constantly an rops to 2-3mA in the re uce power consumption mo e
(exclu ing the RS232 consumption). The power is supplie through the etachable
screw connector with 3.5mm gap on the back plate of the evice. Min the polarity of
the power connector pins. The power connector has reverse polarity an over-voltage
protections.
PRM4 back plate
3.2 Serial connector
The connection of a serial interface is achieve by 9-pin female connector (DB9F).
Depen ing on the position of the jumpers locate on the circuit boar , the evice can
be connecte with the following interfaces: RS-232C, RS-422 an RS-485. If the
jumpers are set for RS-232C, the signal layout matches the DCE si e. The following
table shows the DB9F connector signal layout for ifferent serial connections.
Pin DB9F
connector
RS-232
signals
RS-422
signals
RS-485
signals
1 DCD output
2 RD output -TX -TX/RX
3 TD input -RX
4 DTR input
5 GND - GND GND
6 DSR output
7 RTS input +RX
8 CTS output +TX +TX/RX
9 RI(1) output(1)
Ra io mo em PRM4 868MHz /User's manual V1.6 / 24.05.2011 8

(1) By altering the J7 jumper state it is possible to change the function of this pit to the power
supply input.
(2) On some evices with RS485/422 connection, the signals have been enote as A an B. In
that case, the A signals shoul be connecte to the + signals of the mo em. Vice verse, the B
signals shoul be connecte to the – signals of the mo em.
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3.3 The antenna connector
The antenna is connecte on a SMA female connector on the front plate of the evice.
The antenna shoul be for 863 to 870MHz ban with an impe ance of 50Ω. The
antenna inclu e in the pro uct pack has a 0 Bi gain. In case the a itional range
ought to be achieve the higher gain antennas must be use .
PRM4 front plate
3.4 Signaling lights
The above figure illustrates the layout of the LED signaling lights. The LED functions
are shown in the following table.
Indicator Colour Description
LED Po er Green Constantly on when the power supply is
connecte , the evice's processor is active
an if the re uce power consumption mo e
is set to 0 or 2. If this parameter is set to 1 or
3 this in icator flashes with the frequency of
8Hz.
LED Mode Re On when the evice is in special mo es.
LED Rx Data Green On when receiving ata.
LED Tx Data Re On when sen ing ata.
Ra io mo em PRM4 868MHz /User's manual V1.6 / 24.05.2011 10