RS-232 Cable Connections
Single Tuner
5 GND
2 RXD
3 TXD
RXD 2
GND 5
TXD 3
Control Wiring – Single Unit
9-pin D-sub
female
RS-232
Control Port
Channel Up 4
Channel Down 9
RS-232 wiring for control or programming should only use pins 2, 3, 5. Cables with all pins wired can lock
out front-panel programming and data communication (Pins 4 and 9 are inputs).
Multiple Tuners
Up to nine tuners can be daisy-chained from one RS-232 control port. Remember that you will need to use
the Unit# address in your programming when you control more than one tuner from the same control port.
Set the first unit in the RS-232 chain to the highest Unit#, then wire in sequence to the last tuner in the
chain. The reason for this is that CR tuners use an intelligent data bus - the highest number tuner receives
all commands, and then passes on commands addressed to tuners with lower unit numbers. The next tuner
in the chain does the same, and so on until the last unit.
5 GND
2 RXD
3 TXD
RXD 2
GND 5
RS-232 Wiring – Two Units
Unit 2
9-pin D-sub
female
RS-232
Control Port
Unit 1
9-pin D-sub
female
TXD 3
GND 5
TXD 3
RXD 2
5 GND
2 RXD
3 TXD
RXD 2
GND 5
TXD 3
RS-232 Wiring – Three Units
Unit 3
9-pin D-sub
female
RS-232
Control Port
Unit 2
9-pin D-sub
female
Unit 1
9-pin D-sub
female
TXD 3
GND 5
GND 5
TXD 3
RXD 2
RXD 2
Contemporary
Research
19
232-ATSC Digital HDTV Tuner
