5.1.3
RS485 CONNECTION
For RS485 and RS422 operation, an external adaptor is required. Further information is available from
the sales office
5.1.4
INTERFACE PORT PIN CONNECTIONS
The URT Series is equipped with a 25 way male D connector for all data, audio, power and auxiliary
connections. The pins of this connector are allocated as follows:-
In the event of a polarity reversal on the power supply pins, the circuit board is protected by diodes and
fuses.
When using an external modem, the transmitter can be keyed up by ap5Vdc to pin 4 (RTS).
Open circuit or 0Vdc on this pin will select receive.
Pin 19 can source 3mA to drive an external low current LED to indicate that the Transmitter is active.
The LED should be connected with its anode to pin19 and it’s cathode to Ground.
Pin 23 is reserved for physical compatibility with the CCEN (Channel Change Enable) line on a
CMD400, but this feature is not implemented in the URT500.
Note that pre-assembled cables procured from sources other than RF DataTech may be incompatible
with the pin usage on the URT500 and may cause damage to the URT500 or any other equipment to
which it is connected. It is important to use the correct cables for the radio, both when connecting
traffic and when programming.
5.2 SWITCHES
The two front panel BCD switches select channels or, if both are set to zero, program mode is entered.
When viewing a URT500 with the aerial connector at the top, the left hand rotary switch is the "tens"
switch and the right is the "units" switch, thus to set channel 37 set the left switch to 3 and the right to 7.
URT500 Manual
Page 16 of 42
Rev. C – 6 August 2008
1. GND: GROUND - - - - - - - - - - - - - - - - - - - - - - - - - -o
o- - - - - 14. - Not Used
2. TXD: Transmit Data - - - - - - - - - - - - - - - - - - - - - - - -o
o- - - - - 15. SPARE: Do Not Connect This Pin
3. RXD: Receive Data - - - - - - - - - - - - - - - - - - - - - - - - -o
o- - - - - 16. - Not Used
4. RTS: Request to Send /Tx Enable in Audio Mode - -o
o- - - - - 17. RSSI: Voltage Output in range 0 to +5Vdc
5. CTS: Clear to Send - - - - - - - - - - - - - - - - - - - - - - - -o
o- - - - - 18. +5V: +5Vdc Out
6. DSR: Data Set Ready - - - - - - - - - - - - - - - - - - - - - - -o
o- - - - - 19. TxLED: Anode line for LED
7. GND: GROUND (for Cathode of LED) - - - - - - - - - -o
o- - - - - 20. DTR: Data Terminal Ready
8. DCD: Data Carrier Detect - - - - - - - - - - - - - - - - - - - -o
o- - - - - 21. GND: GROUND (0Vdc Input)
9. GND: GROUND (0Vdc Input) - - - - - - - - - - - - - - - -o
o- - - - - 22. .PWR: +12Vdc Input
10. PWR: +12Vdc Input - - - - - - - - - - - - - - - - - - - - - - - -o
o- - - - - 23. - Reserved for PCCEN
11. XMDI: Audio Input - - - - - - - - - - - - - - - - - - - - - - - - -o
o- - - - - 24. XMDO: Audio Output
12. - Not Used - - - - - - - - - - - - - - - - - - - - - - - - - - - -o
o- - - - - 25. GND: GROUND
13. - Not Used - - - - - - - - - - - - - - - - - - - - - - - - - - - -o