Notes:
1. A pause of at least 50ms must be allowed between command strings (EEPROM programming time)
SINGLE mode does not store the N value in EEPROM. Therefore the unit is inoperative after a
power down until either another valid SINGLE command is received, or mode is changed by a
GOCHAN, SETPAR or SETSER command. SINGLE mode is intended for frequency agile
applications.
2. /SETPAR command should be issued at the end of channel programming to put the module back
into parallel frequency select mode
3. In 458MHz band, channel 12 (458.825MHz) and channel 15 (458.900MHz) are allocated specifically
for fixed alarm and radio keys/vehicle paging applications respectively and should not be used for
general purpose applications.
4. User can modify the frequency table of 128 channels to any desired frequency by changing N, R
values of synthesizer within 1.5MHz of factory set Channel 0 frequency subject to the Radio
Regulatory Band Allocation in the country of intended use.
5. All other frequency, power, analogue input gain and automatic noise squelching adjustment will be
treated as custom variants of the module to be set by factory.
Pin description of VX2M with Modem mode selected
The 'modem' mentioned is a 1200 baud RS232 semi-intelligent unit (Transmit keyed when valid serial data is
present, so no separate TX control needed. Coding in the datastream also permits the receiver to ignore
noise and only output valid serial data). This is a half duplex unit, so collisions between transmitted and
received packets must be dealt with by the user.
Pin
1
Name
Function
MOD TX_ON Open = normal modem operation. Low = constant TX (for test). 10k pullup to 4V
2
3
4
5
MOD NC
MOD NC
RSSI
MOD NC
AF out
Leave open
Leave open
DC level between 0.5V and 2.5V. 60dB dynamic range
Leave open
Modem tones or noise present
6
7
NC
Leave open
8
9
+4.4V out
0V
Regulated DC supply. 75mA max. drain. Present if unit is powered
Ground
10
11
12
13
PGM
Serial programming/configuration input at RS232 level
RS232 data input (true). 10k pullup to 4V
Inverted RS232 data out (to inverting buffer like MAX232)
Leave open
MOD TXD
MOD RXD
MOD NC
VX2Ms on both ends should be configured to required operating frequency using GOCHAN command before
starting to use the internal 1200 baud modem, because the P1-P3 pins will be used as Modem Data pins
and the modem will operate on the last serially selected channel after SETMOD command is used to enable
the Modem.
Note:
Baud rate used for Modem is half that of used for serial configuration. Attached RS232 devices should be set
with the following:
1200bps, 8 Data bits, No Parity, 1/2 stop bits, no flow control
TXD (Pin 3) of a Serial Port can be switched from PGM (Pin C10) to MOD TXD (Pin C11) with no RS232
driver in between. However, MOD RXD (Pin C12) requires an RS232 line driver before it can be connected
to RXD (pin 2) of a serial port. Some of the RS232 line drivers can be powered from the regulated +4.4V out
(Pin C8).
Radiometrix Ltd
VX2M Data Sheet
page 7
RADIOMETRIX [ RADIOMETRIX LTD ]
