Contemporary Research
26
232-ATSC 4 HDTV Tuner
RS-232 Cable Connections
Single Tuner
Contact closures on Pins 4 and 9 can be used with GND for channel up/down control. Using a fully wired null
model cable will not trigger the closure functions.
Multiple Tuners
The easy way is to use an inexpensive IP switch to a control system to connect all the tuners; then use the
control system’s Telnet control setting for the RS-232 commands. No need for Unit numbers, just different
URL addresses.
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
TXD 3
Control Wiring
–
Single Unit
9-pin D-sub
female
RS-232
Control Port
Channel Up 4
Channel Down 9
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
